add RAPIDJSON_NAMESPACE + _BEGIN, _END
Doxyfile: expand RapidJSON namespace macros
*.h: move to namespace macros
namespacetest.cpp: add test for separate namespace
namespacetest: add symbol check to .travis.yml
Merge pull request #193 from pah/feature/custom-namespace

Allow customization of RapidJSON namespace
Add initial CMake support

 * Support for both in-source and out-of-source builds
 * Set library version to 0.12 to map Debian package
 * Add separate options to build tests, examples and documentation
 * Add pkgconfig lookup support (if installed with `make install`)
 * Add CMake lookup support (if isntalled with `make install`)
 * Add Google Test Source lookup
 * Add CTest support for running tests (use `make test` or `ctest -V`)
Fix broken references in documentation
Set separate directory to place binaries
Ignore files generated by CMake
Update readme with changes to CMake build process