Two parts:
1. Specify specific version number for used libraries. Using + is OK in dev phase, when releasing the version should be set.
For Play Services, version 5.0.77 was pulled due to some critical bugs, so I used the latest one 5.2.08 instead (got in a SDK update some weeks ago)

2. Removed unused libraries
 a. support-annotations is added automatically, no need to reference (the path is relative to SDK install dir, so unique). Did not find any other project refrerencing it, but StackOverflow had a comment that SDK annotations was not needed (no link now))
 b. support v4/v13 not needed, as lowest API is 14 anyway
Merge pull request #58 from gerhardol/master.go

Clean up refered libraries