UX: Filter for "Reply key" was not translatable in Transifex

Empty strings are not translatable in Transifex.
Don't set content-disposition header for images

If this header is set for images, clicking the image link causes them to automatically download the file, rather than viewing it inside the browser. This commit forces this behavior only for uploads that aren't images
FIX: 'disable_edit_notifications' will only disable revisions made by the system user
Revert "FIX: unread/new counts out of sync with tabs"

This reverts commit c093187d342c920d8f411b511ee759cca002a856.
FIX: Only use cached topic lists on popState
Merge pull request #2772 from mkayman/s3_store_content_disposition

Don't set content-disposition header for images
Merge pull request #2768 from gschlager/i18n_fix06

UX: Filter for "Reply key" was not translatable in Transifex
TRIVIAL: improve display of the rebake task
FIX: allow staff members to restore withdrawn posts that are flagged
changing the header now that fullname was dropped
Merge pull request #2774 from awesomerobot/master

changing the header now that fullname was dropped
FIX: Clicking on expanded user actions uses user expansion. Also added
integration test.