Fixes #210

…e children are processed, so <script> tag embedded in <polymer-element> is not executed when the latter is upgraded:

modify the instantiation process so that embedded definitions still work (now a `noscript` attribute is required for elements with no script portion);
factor lifecycle methods to support both `createdCallback' and `readyCallback` as we transition to the former

…t, .host, and watches for CustomElements

…l prototype. This pointless code but there's no reason it should fail.

…e deserialized as an object. Addresses issue #215

 - attributes are now reflected to property values at runtime, not only at create time. The rules are the same, the attribute is deserialized to the data type of the property in the element's prototype.
 - `published` properties are now reflected to attributes at runtime. This is done via observation and all published properties are now observed. Properties are serialized directly to strings and object and undefined valued
properties are ignored.

…r of shadowRoot.olderShadowRoot

…res are not polyfilled.

…where MO polyfill is slightly flaky

….com/Polymer/ShadowDOM/issues/189

In conjunction with googlearchive/CustomElements@9b4c5df,
helps address #217.

…th simulated prototype chains (IE10)

… supported for bc.

…be re-declared).

…ative custom elements

…ould be deserialized as an object.