COMP: Remove used flags to JsonCpp build.

For:

CMake Warning:
  Manually-specified variables were not used by the project:

      CMAKE_EXE_LINKER_FLAGS
      CMAKE_SHARED_LINKER_FLAGS
COMP: Only add -Wno-unused-local-typedefs for GCC.

Not found on clang 3.3.
BUG: Fix FindJsonCpp.cmake for finding the include directory.

The current version does not find the proper include directory.
Merge pull request #243 from thewtex/build

Build