Works with Devise <= 2.2.3, added options, kick on update, and send_welcome_email variable

Feel free to pull it down. The big one for me was that it now works with Devise Invitable, and I could control the welcome email from my app. I also included some documentation on how to pass options through to it so that you can pass FNAME, LNAME, and GROUPINGS (as examples - it will accept anything).