Enhanced edit form layout - add fields to Root.Main

Replaced ->push() with ->addFieldToTab('Root.Main', ...)

Form field labels all line up along the left side now.

![Screen Shot 2013-02-13 at 3 23 30 PM](https://f.cloud.github.com/assets/341209/154648/08e6dd96-7624-11e2-88ea-99a8f14461dc.png)

Note: I'm using a Codemirror HTML field in the screenshot which is not included in this module or pull request.