Core/Misc: Remove remaining COMPILER_HAS_CPP11_SUPPORT related macros

Build tested with the following compilers (both with and without PCH):
- gcc-4.7.real (Debian 4.7.2-5) 4.7.2
- Microsoft (R) C/C++ Optimizing Compiler Version 18.00.21005.1

The following files were deleted, because we can use proper std alternatives without additional compiler version checks:
src/server/shared/Dynamic/HashNamespace.h
src/server/shared/Dynamic/UnorderedMap.h
src/server/shared/Dynamic/UnorderedSet.h

^ If COMPILER_HAS_CPP11_SUPPORT is true other #elifs are superfluous. 

UNORDERED_MAP, UNORDERED_MULTIMAP, UNORDERED_SET are replaced to their C++11 std equivalent.
COMPILER_HAS_CPP11_SUPPORT is removed.