Bugfix: Mailing list mode disables PM emails (take 2)

Mailing List Mode disables normal emails, but mailing list mode does not email private_messages.

To avoid this, mailing list mode should only disable emails if they are not private_messages.

There are no tests for this commit as UserNotifications does not appear to be instantiated in the spec suite.
update heroku install docs

1. Redis requires password
2. Automatic asset compilation on by default
3. Tell rails to serve compiled assets
4. Increase garbage collection limit
5. Link to S3 instructions
Merge pull request #2441 from adamloving/update-heroku-docs

update heroku install docs
Merge pull request #2439 from peternlewis/mailing_list_mode_disables_private_message_emails2

Bugfix: Mailing list mode disables PM emails (take 2)
Make it possible to add multiple CORS origins in discourse.conf and docker yml files
move bio to UserProfile from User
update import script to save bio to UserProfile
FIX: crawler versions of the page need the updated bio relationships.