YouTube player enhancements

This pull requests includes a number of bug fixes and enhancements to the YouTube players, most notably:

1. Adds a number of *automated tests* over the four different YouTube player configurations

![image](https://f.cloud.github.com/assets/2079548/2350368/a6579522-a56f-11e3-957a-7d6b38ba3fd0.png)

2. Adds basic *`readyState` support* to the PluginMediaElement

![image](https://f.cloud.github.com/assets/2079548/2350392/0563103c-a570-11e3-9dbe-67374aabafac.png)

3. Makes the 'canplay' and 'loadedmetadata' events *consistent across Flash and YouTube plugins*