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 
You don't need to manually bubble the event, the DOM will do this for you :)

`event.target` will always give you whatever was clicked, independent of where we are in the bubbling/capturing phases.

`event.currentTarget` will give you a chance to capture the event as it bubbles up the DOM tree, which I think is what you're trying to do.

I think this will do what you need:
```coffeescript
document.addEventListener eventType, (ev) ->
  return unless currentTarget = ev.currentTarget
  if currentTarget.nodeName in ["A", "BUTTON"]
    if nodeIsDisabled(currentTarget)
      ev.preventDefault()
    else
      ev.clickTarget = currentTarget
      handler(ev)
```