Issue #509 Implemented RtReleaseAssetsITCase, corrected URI in
RtReleaseAsset
issue_503
Issue #557 Implemented Contents#raw()
Issue #557 Implemented Content.Smart#content() method
Issue #558 Contents#update returns a RepoCommit
Issue #557 Added unicode characters to test, MkContent to use Base64.
#515 Tags implementation

RtTags, RtTag, MkTags, MkTag, plus unit and integration tests.
Merge branch 'master' into 515
#515 removed the puzzle
Merge branch 'master' into 558
Issue #558 Added unit tests for checking returned RepoCommit
Issue #509 Updated Javadoc comment
Issue 534. Test RtRepoCommitsITCase.compareCommitsPatch() implemented.
Issue #592 NotNullTest was implemented
Issue #592 Functional fixes
Merge remote-tracking branch 'origin/master' into 557

Conflicts:
	src/test/java/com/jcabi/github/ContentTest.java
#515 fixes
#515 style fixes
#515 removes one time variables
#515 removed another one time variable