Allow controller to pass params to reset password email

These changes allow the password controller to pass parameters to the reset password email via the optional mailer arguments added in devise 2.2.0.

Unfortunately this means you shouldn't really call `send_reset_password_instructions` on the class method, because that method already takes a hash of arguments used to find the resource. I could have used an optional `mailer` key in that hash, the same way rails allows for a `html` key in hash options for things like `form_for` etc, but I thought this was a better option. Happy to discuss any alternative ideas people might have.

Also, I only implemented controller parameters for the passwords controller, but the framework is there for confirmable and lockable as well. I just wasn't as familiar with those controllers as I don't use them, so I didn't fell 100% comfortable in changing them.