User accounts attempt 2

Hey all,

I've gotten two User Account scenarios passing! The other three are not as important to have complete for this weekend. There is still no real UI yet - the only user interface files so far are the ones supplied by Devise in `app/views/devise/`. For now, I'm focusing on getting the back-end in shape before filling out the front-end with what's needed for the bare minimum functionality.

A lot of this is also configuration file updates - some of it is directly related to these two User Account scenarios (like configurations for ActionMailer, the library that sends email for us), but some of it is more general, usable for this and other updates in the future.

If there's any files you take a look at in all of this, check out the two step definition files in `features/step_definitions/`. The `user_steps.rb` file includes step defintions I came up with myself, and `email_steps.rb` includes a bunch of pre-made steps related to emails that we can use either in feature files or in step definitions. It might still be hard to understand, but I hope the user step definitions are at least generally readable enough so that you can see the conversion from plain English to code.