LB-382: Blog provider plugin
* chained blogs via the superdesk-source && type
LB-382: Blog provider plugin
LB-91: Refactor admin templates

Added missing __init__.py
LB-91: Refactor admin templates

Added missing __init__.py
Merge branch 'devel' into 368-chained-blogs
LB-91: Refactor admin templates

Avatar issues.
LB-321: Avatar images don't look good on some pages in Chrome

Fixed.
LB-321: Avatar images don't look good on some pages in Chrome

fixed for manage collaborators.
LB-368 : Chained blogs - plugin
Merge remote-tracking branch 'origin/368-chained-blogs' into 350-chain-blogs
Implement subscribe checkbox for external blogs.