Add the ability to send emails to devs of paid apps (bug 896034)

That checked the `enable_new_regions` checkbox or not.
Email paid-apps devs with unreviewed statuses (bug 902065)

Equivalent to STATUS_UNREVIEWED, STATUS_PENDING, STATUS_NOMINATED,
STATUS_PURGATORY, STATUS_PUBLIC, STATUS_PUBLIC_WAITING
tweak add-ons search to search tags (bug 809590)
Merge pull request #934 from ngokevin/search

tweak add-ons search to search tags (bug 809590)
Bump app-validator

Like a million fixed bugs.
Don't consider deleted versions in reviewers updates chart (bug 900897)
Removes explicit ID from migration 638.
Merge pull request #971 from davidbgk/902065-send-email-pending

Email paid-apps devs with more statuses (bug 902065)
new reviewer tools nav between queue types (bug 839400)
Add additional settings to identitystage
Merge pull request #958 from davidbgk/896034-send-email-region-added

Add the ability to send emails to devs of paid apps (bug 896034)
hide Reviewers Tool pill nav if reviewer has only apps permission (bug 903072)
default to queue when toggling apps/themes tabs (bug 903124)
Remove NEWRELIC_INI from identitystage settings.
fix theme breadcrumbs
Allow API consumers to edit collections (bug 894585)
Allow API consumers to reorder applications in a collection (bug 894591)
DRF the global stats
Add NATIVE_BROWSERID_VERIFICATION_URL and NATIVE_BROWSERID_JS_URL to identitystage settings
Added HTML receipts (bug 890046)