Added accordian multi-tab opening functionality

[foloed]

Multiple tabs can be opened all at once on accordion view.

[openam]

@foloed I'm not sure if I like this. I don't like having multiple accordions open at the same time. You can't do it with tabs. With that said I understand it makes more sense to possibly allow it in the accordions.

If you want this in could you make it so that it's an option that gets passed in when you start it? Maybe we should do something like this:

fakewaffle.responsiveTabs( {
  'sizes'  : [ 'xs', 'sm' ],
  'toggle' : false
} );

The options should be backwards compatible with just passing in the sizes, e.g. fakewaffle.responsiveTabs( [ 'xs', 'sm' ] ); should still work.

Also, you should squash all these commits into one commit, and rebase it.

[openam]

This would address #44.