Merge branch 'release/0.3.8' into develop
Updated dependency version GAE 1.7.7 -> 1.8.0
Removed visitor method about Search API.

Search API's pb classes was removed or moved...
[maven-release-plugin] prepare release memvache-0.3.9
[maven-release-plugin] prepare for next development iteration
Merge branch 'release/0.3.9'