Fix missing includes for boost 1.56.0

src/ripple/core/impl/Config.cpp

@@ -29,6 +29,7 @@
 #include <boost/format.hpp>
 #include <boost/regex.hpp>
 #include <fstream>
+#include <iostream>
     
 namespace ripple {
 

src/ripple/net/impl/RPCCall.cpp

@@ -23,6 +23,7 @@
 #include <ripple/net/RPCErr.h>
 #include <ripple/net/RPCUtil.h>
 #include <boost/regex.hpp>
+#include <iostream>
 
 namespace ripple {
 

src/ripple/peerfinder/impl/Checker.h

@@ -21,7 +21,8 @@
 #define RIPPLE_PEERFINDER_CHECKER_H_INCLUDED
 
 #include <beast/asio/shared_handler.h>
-
+#include <boost/system/error_code.hpp>
+    
 namespace ripple {
 namespace PeerFinder {