[cmake] Force the usage of C++11

CMakeLists.txt

@@ -1,6 +1,12 @@
 PROJECT(LIBCAPS)
 CMAKE_MINIMUM_REQUIRED(VERSION 2.4)
 
+IF(CMAKE_CXX_COMPILER_VERSION VERSION_GREATER "4.7")
+    ADD_DEFINITIONS(-std=c++11 -DBOOST_NO_CXX11_SCOPED_ENUM -DBOOST_NO_SCOPED_ENUMS)
+ELSE()
+    MESSAGE(ERROR "The CAPS client library requires gcc version 4.7 or higher")
+ENDIF()
+
 SET(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/Modules)
 
 FIND_PACKAGE(Boost REQUIRED)