Issue 496 MkEvent.json created_at JSON element added.
Merge branch 'master' of github.com:aistomin/jcabi-github into Issue-496
Issue 496 MkEvent.json created_at JSON element hardcoded value replaced with current time value.
Merge pull request #559 from aistomin/Issue-496

#559: pull request Issue 496 MkEvent.json created_at JSON element added.