Extract methods to improve flog score of TopicView
Generate avatars with transparent background

Generate avatars with transparent background (for .png images) or with white background (for others).
only the host part of an email address is case insensitive
Replace Clockwork with Sidetiq
Add ScreenedUrl. Rename BlockedEmail to ScreenedEmail.
Merge pull request #1330 from ZogStriP/emails-can-be-mixed-case

only the host part of an email address is case insensitive
Finish renaming blocked emails to screen emails
Merge pull request #1328 from abbat/patch-1

Generate avatars with transparent background
FIX: performance regression on activity streams
Merge pull request #1317 from novemberkilo/master

Extract methods to improve flog score of TopicView
Merge pull request #1309 from stephankaag/sidetiq

Replace Clockwork with Sidetiq
Merge pull request #1331 from ZogStriP/fix-avatars-on-activity-stream

FIX: performance regression on activity streams
make code climate a bit happier
minor refactoring
FIX: avatars in quotes/oneboxes

Avatars in quotes/oneboxes are still pointing to the old
`/users/:username/avatar(/:size)` route.
So, this adds back the old avatar route for the transition period.
Merge pull request #1323 from ZogStriP/fix-avatars-in-quotes-in-already-cooked-posts

FIX: avatars in quotes/oneboxes
Add oneboxers for popular learning resources
FIX: N+1 query for avatars
Updated Dutch translation
Merge pull request #1326 from sanderdatema/dutch_translation

Updated Dutch translation