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.
Added ability to add private talk comments.
Merge remote-tracking branch 'akrabat/dbgen_duration'
Merge remote-tracking branch 'akrabat/dbgen_duration'
Merge branch 'master' of GitHub:joindin/joindin-api
Merge remote-tracking branch 'richsage/private-comments'
Merge branch 'master' of GitHub:joindin/joindin-api
making the full name field optional, this can happen when a user signs in with some other social network
Merge pull request #27 from lornajane/full-name-fails-test

Fix the test that expects full name to be populated