Kinto-emailer

**Bug fixes**

- Don't block on Pyramid 1.8 anymore. (46)

**Bug fixes**

- Fix crash when creating bucket with ``POST /buckets`` (fixes 43)

**New features**

- Add a ``validate_setup.py`` script to check that server can actually send emails
- Add a ``kinto-send-email`` command to test the configuration (fixes 35)

**Bug fixes**

- Fix sending notifications by decoupling it from transactions (fixes 38)

**New features**
- Support configuration from bucket metadata (fixes 27)
- Send mail to local Maildir queue if `mail.queue_path` setting is defined (ref 3)

**Bug fixes**
- Fix support of batch requests (fixes 24)

**New features**
- List of recipients can now contain groups URIs. The principals from the specified
group that look like email addresses will be used as recipients (fixes 6)
- Support new variables like server root url or client IP address in email template (fixes 22)
- Add some validation when defining kinto-emailer settings in collections metadata (fixes 21)

**Initial version**
- Use a list of hooks to configure emails bound to notifications (fixes 11)
- Support _kinto-signer_ events (fixes 14)