- Updated CMake configuration
  + Add preprocessor definition to ensure Boost does not use rvalue references (this allows the integration tests to build without c++11).
  + Added a check to validate CMAKE_CXX_COMPILER_VERSION variable existence and added a workaround to get the compiler version from gcc (CMAKE_CXX_COMPILER variables were not added until 2.8.x)
  + Ensured the LIBUV_INCLUDE_DIR discovered by the parent was used for the unit tests (fixes unit test build)
- Changed INT64_MAX/MIN to use c++ numeric limits
- Updating TavisCI configuration
  + Install libssh2 and build Boost v1.55 from source
  + Build tests and run unit tests (increases build status information)

NOTE: CMake configuration needs some more TLC to work properly on CentOS5.  The LIBSSH2 package available by the default yum repositories is v1.0.0 and method calls used by the integration tests were not available until v1.2.5.  CMake configuration should check for LIBSSH2_ROOT_DIR similar to LIBUV_ROOT_DIR.