Refactor ripple_overlay:

* Use rvalue move to receive accepted sockets
  * Split asio dependent APIs to their own class and file
  * Update documentation
  * Organize code into different files
  * Make some members private
  * Rename things for clarity

src/ripple/sitefiles/api/SiteFile.h

@@ -20,6 +20,11 @@
 #ifndef RIPPLE_SITEFILES_SITEFILE_H_INCLUDED
 #define RIPPLE_SITEFILES_SITEFILE_H_INCLUDED
 
+#include "Section.h"
+
+#include <string>
+#include <unordered_map>
+
 namespace ripple {
 namespace SiteFiles {
 
@@ -28,7 +33,7 @@ class SiteFile
 public:
     SiteFile (int = 0); // dummy argument for emplace
 
-    typedef boost::unordered_map <std::string, Section> SectionsType;
+    typedef std::unordered_map <std::string, Section> SectionsType;
 
     /** Retrieve a section by name. */
     /** @{ */