basic working JSQ6
Message delete menu

https://github.com/jessesquires/JSQMessagesViewController/issues/569
Added Lock and Delivered icons
Show account avatars in conversation
Show message error in avatar
Moved JSQMessagesViewController to latest commit

This fixes a bug with the contentOffset of the collectionView but
should be available in v6.1.1
Moved delegate callback from cell delegate
Added comments and links to github issues
Added comments to avatarData and avatarImage
Move avatar image creation to OTRImages
Merge pull request #287 from chrisballinger/JSQ6

Updated JSQMessagesViewController to Version 6+