LPS-44056 Enable a11yhelpbtn plugin

Hey Nate,

I finally got around to finish what we discussed in https://github.com/natecavanaugh/liferay-portal/pull/2137#issuecomment-35517038 about the a11y button for CKEditor.

Please, let me know if you think we can still improve this.

BTW: I added a last commit with some general source formatting because your source-formatter tool was complaining about it. However, the pattern `<%@ taglib uri="http://liferay.com/tld/aui" prefix="aui" %>` is all over the portal. Should we change those everywhere? Or should we just ignore this? Feel free to remove the last commit if we go with the latter.
![screen shot 2014-06-05 at 3 52 54 pm](https://cloud.githubusercontent.com/assets/905006/3188231/c93a1930-ecb8-11e3-9139-087370ce4471.png)

Thanks!