Add CMake support:

cmake support in rippled. Currently supports:

 * unity/nounity debug/release
 * running protobuf
 * sanitizer builds
 * optional release build with assert turned on
 * `target` variable to easily set compiler/debug/unity
    (i.e. -Dtarget=gcc.debug.nounity)
 * gcc/clang/visual studio/xcode
 * linux/mac/win
 * gcc 4 ABI, when needed
 * ninja builds
 * check openssl for acceptably recent release
 * static builds

TBD:
 * jemalloc support
 * count

Notes:
 * Use the -G"Visual Studio 14 2015 Win64" generator on Windows. Without
   this a 32-bit project will be created. There is no way to set the
   generator or force a 64-bit build in CMakeLists.txt (setting
   CMAKE_GENERATOR_PLATFORM won't work). The best solution may be to
   wrap cmake with a script.

 * It is not possible to generate a visual studio project on linux or
   mac. The visual studio generator is only available on windows.

 * The visual studio project can be _either_ unity or
   non-unity (selected at generation time).  It does not appear possible
   to disable compilation based on configuration.

 * Language is _much_ worse than python, poor documentation and "quirky"
   language support (for example, generator expressions can only be used
   in limited contexts and seem to work differently based on
   context (set_property can set multiple values, add_compile_options
   can not/or is buggy)

 * Could not call out to `sed` because cmake messed with the regular
   expression before calling the external command. I did not see a way
   around this.

 * Makefile generators want to be single target. It wants a separate
   directory for each target type. I saw some mentions on the web for
   ways around this bug haven't look into it. The visual studio project
   does support debug/release configurations in the same project (but
   not unity/non-unity).

src/ripple/app/main/Application.cpp

@@ -73,7 +73,6 @@
 #include <ripple/rpc/Context.h>
 #include <ripple/rpc/RPCHandler.h>
 #include <ripple/shamap/Family.h>
-#include <ripple/unity/git_id.h>
 #include <ripple/websocket/MakeServer.h>
 #include <ripple/crypto/csprng.h>
 #include <ripple/beast/asio/io_latency_probe.h>
@@ -807,7 +806,7 @@ public:
     void onStart () override
     {
         JLOG(m_journal.info())
-            << "Application starting. Build is " << gitCommitID();
+            << "Application starting. Version is " << BuildInfo::getVersionString();
 
         m_sweepTimer.setExpiration (10);
         m_entropyTimer.setRecurringExpiration (300);

src/ripple/unity/git_id.cpp

@@ -1,32 +0,0 @@
-//------------------------------------------------------------------------------
-/*
-    This file is part of rippled: https://github.com/ripple/rippled
-    Copyright (c) 2012, 2013 Ripple Labs Inc.
-
-    Permission to use, copy, modify, and/or distribute this software for any
-    purpose  with  or without fee is hereby granted, provided that the above
-    copyright notice and this permission notice appear in all copies.
-
-    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
-    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
-    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
-    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
-    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-*/
-//==============================================================================
-
-#include <ripple/unity/git_id.h>
-
-namespace ripple {
-
-std::string gitCommitID() {
-#if defined(GIT_COMMIT_ID)
-    return GIT_COMMIT_ID;
-#else
-    return std::string();
-#endif
-}
-
-}

src/ripple/unity/git_id.h

@@ -1,32 +0,0 @@
-//------------------------------------------------------------------------------
-/*
-    This file is part of rippled: https://github.com/ripple/rippled
-    Copyright (c) 2012, 2013 Ripple Labs Inc.
-
-    Permission to use, copy, modify, and/or distribute this software for any
-    purpose  with  or without fee is hereby granted, provided that the above
-    copyright notice and this permission notice appear in all copies.
-
-    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
-    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
-    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
-    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
-    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
-*/
-//==============================================================================
-
-#ifndef RIPPLE_UNITY_GIT_ID_H_INCLUDED
-#define RIPPLE_UNITY_GIT_ID_H_INCLUDED
-
-#include <string>
-
-namespace ripple {
-
-/** Get the git commit id from the git repo from which this was compiled. */
-std::string gitCommitID();
-
-}
-
-#endif