consolidate new post form variants into single client-side template/view

@marcotuts @gwprice 

*not yet ready for merge*  views.py still needs some cleaning up.  however, the templates and backbone views are where they need to be to move forward.

in general i agree with the pattern of rendering into placeholders via jquery.  in this case it could have worked either way, but i chose this approach because it would save a rendering operation on the browser, which felt slightly more efficient.  i confess i am not sure really how much difference it makes, and can easily switch back.