Welcome email feature in settings.yml

PT story: https://www.pivotaltracker.com/story/show/73659532
Added feature for welcome email into setting.yml: 
production - enabled
development - disabled
test - enabled

This PR has changes from PR#460, to fix CI for capybara js tests.
Good point.  It should be After hook.  Thinking about it, I think we should just increase the wait time in the env.rb and get rid of the hooks, since it only applies to javascript drivers anyway.