Fixes to coexist with Polymer.

- Don't depend on HTML*Element.name or HTML*Element.toString().
  Polymer redefines HTMLElement such that HTMLElement.name == "i".

- WebKitMutationObserver doesn't work when Polymer is loaded; use MutationObserver instead.

Added a test for Polymer/Delite compatibility, and
added Polymer to the "devDependencies" section of bower.json, just for testing purposes.

Note that I made a functional test because unit tests aren't sandboxed, and I don't want
Polymer loaded when the other tests run.

Fixes #91.
add tests for register() error reporting