Modified email text as per Kate's request
Rake task to send "thank you" emails for added sites.

NOTE: this is NOT in deploy-tasks.sh as we don't want to accidentally
run it twice.  Just a note that when deploying this feature, we'll want
to run the following command manually:

heroku run rake acres:oneoff:send_added_emails
removed unused port option from config
added URL to email signoff
added some env vars to travis.yml to try and make it pass
Merge pull request #62 from Skud/email

Email