LB-22: Create a design on timeline, collaborator and edit for sources

In youtube post template two tags are added, after tool-box-right.
Figure (for avatar) and div.post-info (for username and time). This
should be done in all other templates (flickr, instagram, twitter,
soundcloud, google). Normal and qoute posts, don't need this, as they
already have it.
Merge branch 'devel' of dev.sourcefabric.org:superdesk into devel