LB-1268: Add on blog config the option to set verficication as enable / disabled

Done
LB-1262: As Admin I want to be able to enable/disable verification flow for every blog.

Added for items in chain.
LB-1162: As an editor, I want to set verification info on posts from timeline

Fixed for timeline.
Merge pull request #514 from nistormihai/citizen-hidden

Citizen hidden
Merge branch 'cit-verif-toggle' of https://github.com/vladnicoara/Superdesk into cit-verif-toggle
LB-1262: As Admin I want to be able to enable/disable verification flow for every blog.

done on chain blog source (filtering and the setter)
Merge branch 'cit-verif-toggle' of https://github.com/vladnicoara/Superdesk into cit-verif-toggle