Equals method for Github.Time
Added test for Github.Time.
Moved Github.Time#equals tests to RtGithubTest. Changed test method comments. Removed magic number.
Updated comments.
Merge branch 'master' of github.com:jcabi/jcabi-github into issue-840
Merge pull request #843 from hariso/issue-840

#843: pull request Resolved issue #840: Github.Time has no equals method.