Password reset

1) add PasswordResetController
2) add views for PasswordResetController
3) add specs for PasswordResetController
4) add code for PasswordResetController
5) add validation on password length

Please approve.
I had a chat to a few other devs and are we agreed that `find_by(email: email)` is the standard now rather than `where` if looking for a single resource. Also you are right, that `find_by_email` has been depreciated. :-)