Don't set the title if the user has not overridden it
Updated Documentation
Ensure content is loaded before dropping content on other content
Templates with <li> as a parent must not have a space

before the first element in the template. Otherwise the list item will
render on a separate line
Cleaned up models and views a bit.

Mediatypes for EPUBs are out of this branch, new content gets a
temporary id, and book editor can be configured for the default
mediaType for new content
Fixing DnD for book editing
Loads controller to register default media types
Add an "add" button for creating new content
Refactored MEDIA_TYPES factory and BaseModel

 so Tree navigation and DnD is more uniform
Sidebar now shows Books and Folders that can be edited directly

Simplified the MEDIA_TYPES even further so it only contains a mapping
from mediaType to constructor.
Load content in the sidebar so it is navigable