attempt to add proper support for delegated events

Fixes #48 (I hope)

- removes `partial-graft` since it's not very useful, and eclipsed by `tg-remote`
- properly perform `tg-remote` actions on buttons/links with DOM content inside of them

So, turns out it's pretty hard to make a delegated event elegantly in pure JS!  I think this is correct.  Didn't realize until now just how much `$(document).on(".some-selector", ->)` bought you.  Would you like to look this over?  I can add some tests after the fact (have been manually testing using the example app)

cc @kurtfunai @celsodantas @nsimmons @patrickdonovan @pushrax 
Arg, yeah; I had that wrong. `currentTarget` will always give you the node listening for the event, so it's always going to give you `document` in this case.

I think what you had already might be the best you can do.