Fix the boolean return of Store::remove()

 - std::map::erase() "For the key-based version, the function returns
   the number of elements erased, which in map containers is at most 1."
Fix the CMake for GCC 4.6

 - GCC 4.4, 4.5 and 4.6 uses the flag "-std=c++0x" instead of "-std=c++11"
 - GCC 4.7 and above can use any two of them

NOTE: this is only part of a fix for building against GCC 4.6 ; I will also provide a fix for the source code
NOTE: GCC 4.6 is used under Ubuntu 12.04 current LTS, and so it is the default for Travis Continuous Integration free services
Fix the CMake for MSVC
Fix CMake of examples for MSVC
Fix msvc build

 - constexpr only supported from VS2013
 - custom string literals not supported, even in VS2013 (only in last CTP preview)
Merge branch 'origin/fix-msvc-build'
Merge branch 'origin/fix-cmake-gcc-46'
Merge branch 'origin/fix-store-remove-return'