Install devise
rails generate devise:install
rails generate devise User
Use legacy table name
Don't try to create existing email field
Don't try to add index to TEXT column
Run devise migration
Send mail to mailcatcher in development
Configure default mail sender for devise
Rename PHP app's password DB column to legacy_password

This allows devise on Rails to use the password attribute on its
user object.

It also makes it clear that this password is deprecated and shouldn't
be used if possible.
Replace custom authentication with devise
Log out via devise
Use devise to change your password
Remove unused view now we're loggin in with devise
Remove this comparison - it will fail now we redirect to devise
Don't test the login process now we're using devise

But still ensure we can see the same settings page when we're logged
in.
Login using Warden in our tests
Don't test chaning passwords - we're doing this via devise now
Merge pull request #190 from openaustralia/issue174

Use devise for user authentication in Rails. Fixes #174