Revert "Revert "show 'Installed' for a button if we know a user has installed it in the past (bug 815426)""

This reverts commit 12c40e814dcd350c1d7b7b808be391b56b9b84a7.
define installed properly
buttony sexiness (bug 829778)
drop temp tables (bug 832767)
Upgrade to celery 3.x. (bug 823510)
Revert "Upgrade to celery 3.x. (bug 823510)" ... for science!

This reverts commit b4c410f8097ea45800be0ba80b36224eb1cb8d55.
Extended timeout for heroku apps (bug 833756)
amo validator pickle
Attempt to fix bug 833677

This block of code wasn't getting run.
do not initialize payments JS within Reviewer Tools (bug 833677)
do not let django_debug_toolbar choke on an anonymous amo_user