Added anytime querying of media match state and also promise to allow functions to wait for rubberband to finish loading 

Some simple additions, I hope you like them.

1. `$.rubberband("state")` now returns the state data at any time, which means scripts which dynamically run at some arbitrary time don't need to wait for the snap event to know what state the page is in.
2. `$.rubberband("loaded")` now returns a promise so that scripts can queue functions which must wait until rubberband has determined the above state before running.

Nothing terribly complicated.

Cheers
Alastair