Standardize on CMAKE_INSTALL_PREFIX for specifying installation directory
Defer to original default value if CMAKE_INSTALL_PREFIX not specified
Merge remote-tracking branch 'upstream/master' into custom-nupic.core-location

Conflicts:
	src/CMakeLists.txt
Add deprecation warning re: PROJECT_BUILD_RELEASE_DIR
Merge pull request #170 from oxtopus/custom-nupic.core-location

Standardize on CMAKE_INSTALL_PREFIX