Merge pull request open-source-parsers#313 from cdunn2001/master

`-std=c++11` for gcc builds too

There was an issue with Travis, but we seem to be past that now.

We were using only -std=c++0x for gcc, as you can see in the diff.

resolves open-source-parsers#134

Author: cdunn2001

CMakeLists.txt

@@ -100,7 +100,7 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Wshorten-64-to-32")
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
   # using GCC
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x -Wall -Wextra -pedantic")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Wextra -pedantic")
 endif()
 
 IF(JSONCPP_WITH_WARNING_AS_ERROR)