Updated rspec-rails to 2.12

so we get named subjects.
Use valid hostname in test environment
Fix broken link in BB dissolution mailer

with tests to prevent us ever again suffering this shame.
https://www.pivotaltracker.com/story/show/34583559
Test all mailers for valid links

https://www.pivotaltracker.com/story/show/34583559
Fix accept link in BB invitation mailer

It points to the requesting org's profile, instead of trying to accept the request from inside the email.
https://www.pivotaltracker.com/story/show/34583559