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

That checked the `enable_new_regions` checkbox or not.
remove settings assignment in TestEmailApi
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)