This adds the ability to filter user signup with a whitelist
instead of or in addition to a blacklist.

Fixes #817

make regeneration worker unique, (only schedule/execute once at a time)

do not re-create a dynamic class on each feed push call, make sure redis-rb uses hiredis

adjusted to allow choosing it, yet

reinsert it when someone boosts it

status is not in the system at time of distribution; fix #607 - reset privacy
settings to defaults when cancelling replies

redis-backed "mentions" timeline as redundant (given notifications)

fix ProcessFeedService pushing status into distribution if called a second time
while the first is still running (i.e. when a PuSH comes after a Salmon slap),
fix not running escape on spoiler text before emojify

Federate spoiler_text using warning attribute on <content /> instead of a <category term="spoiler" />
Clean up schema file from accidental development migrations

affected, replaced onClick handler with onMouseUp/Down to detect text
selection not trigger onClick handler then

background as well since it's a computationally expensive

now return empty hash instead of throwing a 404 error. When following,
merge into timeline will filter statuses

application website validation, don't link to app website if website isn't set,
also comment out animated boost icon from #464 until it's consistent with non-animated version

with YAML-defined defaults. Add admin page for editing global settings. Add "site_description"
setting that would show as a paragraph on the frontpage

resolving the confusion from self-chain replies ultimately linking to a
non-self status. Adjust filters

Reflect "requested" relationship in API and UI
Reflect inability of private posts to be reblogged in the UI
Disable Webfinger for locked accounts

who don't follow them