Specify CELERY_RESULT_BACKEND in default_settings
Merge branch 'master' of /git/btbv2 into HEAD
Merge branch 'master' of /git/btbv2 into HEAD
Merge branch 'master' of /git/btbv2 into HEAD
Merge branch 'master' of /git/btbv2 into HEAD
Merge branch 'master' of /git/btbv2 into HEAD
Add zip code extractor
Merge branch 'master' of v2.betweenthebars.org:/git/btbv2
Add new 'returned' and 'refused' letter types

Also, fix a long standing annoyance bug where browsing a non-existent
tag throws a 500 instead of 404.
Default result backend should be "amqp"

Also, fix the broken blank postcard generator.
Case insensitive reply codes, 404 not 500 for missing tags
Don't double-send on comment edits.
Improve language for refused originals
Small improvements to FAQ.
Fix reply codes again
Fix requirements post merge
Fix adult content template name bug
Restrict moderator notices to non-self-link things
Include transcriptions in self-link exclusion
Don't spam subscribers with document-less comments