Fixes a component's template having directly nested live-binding sections.

[imjoshdean]

Fixes #1593.

This fix makes sure that a component's template with "directly nested" live-binding sections like:

can.Component.extend({
  template: can.stache("{{#if foo}}<span/>{{/if}}")
})

Are able to be torn down when their parent component is removed from the page.

The fix was to give a component a nodeList that it passes to its template. When the component is removed, it will unregister its nodeList, which will teardown any "directly nested" live-binding sections.

While I was in can.Component, I consolidated the teardown code to work off only one "removed" event (or the control's destroyed event).