WIP Tam multiple groups

~~(For the love of god do not merge this)~~

Oh man... I'm so lost... 

- I was working off the hartl tutorial ( http://ruby.railstutorial.org/book/ruby-on-rails-tutorial#cha-following_users ) in the hopes that it would help with the has_many through association I set up. 
- I did all the database migrations etc...
- a person is now successfully associated with a membership (ex: p = Person.find(1), p.groups => an array of the group, p.memberships => an array of the membership which includes the correct group id)
- the join/leave buttons are not working. With the join button I get the following error:
![screen shot 2014-04-04 at 17 28 44](https://cloud.githubusercontent.com/assets/4237285/2617079/de51266e-bc0d-11e3-9a88-bc42d050be65.png)
- with the leave button I get the following error (perhaps because my partial is not recognizing current_person?):
![screen shot 2014-04-04 at 17 28 25](https://cloud.githubusercontent.com/assets/4237285/2617085/f035b07a-bc0d-11e3-8a65-5526a72736d3.png)
- I'm tired and confused and need a second/third/fourth pair of eyes. Am I completely off base here?
- @lislis I created my own branch off of yours because... well.. this messiness speaks for itself.