Remove entity-factory functionality

The entity-factory functionality is currently broken, and there is
no point in having it in the first place. (Every javascript programmer
already knows how to create reusable code: Create a function!)

Deleting the functionality was discussed and endorsed here:

https://groups.google.com/d/topic/craftyjs/1ESEbI09S7s/discussion
Merge pull request #434 from sbyrnes321/no_factory

Remove entity-factory functionality