Add event comment posting to API.
Added user's full name into comment saving.
Creating new talk comment returns comment URI.
Fixes JOINDIN-332.
Return location header with the new comment URI.
Stopped the tests from failing if the Twitter username is null in the API response
Merge remote-tracking branch 'richsage/post-event-comment'
Merge remote-tracking branch 'richsage/JOINDIN-332-comment-uri'
Merge remote-tracking branch 'magicmonkey/fix_twitter_test'
sorting the talks collection by date/time
Add talk duration to dbgen

The duration column was addded to the talks table does not allow null,
so we have to set it to something. For now, we default to 60 minutes.
Merge remote-tracking branch 'akrabat/dbgen_duration'