Rename existing mailing list stuff

Since we're not really giving people the ability to "opt in" on this, it
seemed confusing to leave the code structured like that. Now we can just
check if they have not opted out to determine if we can send mail.
Add ability to send mailing list type messages
Add unsubscribe link
Add message about unsubscribing
Commit for testing mailing list
Mailing list tweaks
Update email templates to better handle html
Change copy for user facing mailing list stuff
Remove test email data - We'll do it live!
Update unsubscribe info message
Merge branch 'master' into mailing-list

Conflicts:
	urls.py
Refactor unsub info message
Don't email users without domains

Remove the error catching for users who do not have domains and instead
just filter them out in the couch view since we don't need to contact
all the people who aren't even using the site.
Refactor django message call
Merge branch 'master' into mailing-list

Conflicts:
	corehq/apps/hqadmin/views.py
Merge pull request #806 from dimagi/mailing-list

Mailing list feature