Squashed 'libraries/protobuf/' content from commit 4f0cc53

git-subtree-dir: libraries/protobuf
git-subtree-split: 4f0cc534a4429e439f9bb1d78af7612a96197d03
Merge commit 'c5cfadbcb41d56355d06d9b1546bbcb81f3ecef3' as 'libraries/protobuf'
Add CMake files.
Switch from gtest 1.6 to 1.7.