LB-739: Can not publish some FB posts

Added a warning message if FB post is > 3000 chars saying that the post
has been trimmed to fit that
LB-743: User Comments - option to disable the user comments per blog

fixed error if no embedconfig json avalible.
LB-755: Comments seem stopped working

Hide comment message box.
Merge pull request #214 from petrjasek/lb-755-comment-box

Lb 755 comment box
Merge pull request #213 from vladnicoara/facebook-post

LB-739: Can not publish some FB posts