Fix #270

Multi tag filtering has been removed: this commit removes its relative tests.
Merge pull request #274 from nimiq/fix#270

Fix #270
better user moderation, banning user removes all their posts and gravatar image, more embedding options
source must be over https
removed new embedder, would not work over https
added optional banners
Merge branch 'master' of github.com:ialbert/biostar-central
adding optional banners
more work on banner
added trigger based on user reputation
more work on banners
minor css change
minor version change, data migration is necessary for working sites. Added daily digest and weekly digest options to user profiles.
work on daily and weekly digests
Merge branch 'master' of https://github.com/ialbert/biostar-central into develop