Kill flask

This is dependent on #228 -- I built off of that to avoid merge conflicts later. Let's get that merged first.

As stated in the last commit, the logic isn't that different - it's pretty much what you get when you un-nest all of the decorators. It's a good bit cleaner now, and removes our dependency on flask, which is nice for a couple reasons:

* Flask pulls in a lot of dependencies, mnostly things like Jinja2 that we aren't using
* Flask does some things that make usage in multi-threaded/forking environments tricky to think about -- the new implementation is pretty straightforward in that regard.

This needs careful testing, but lets start the review now.
Ha! Not an intentional one!

Quoting gsilvis (2014-09-24 13:45:31)
>    In haas/api.py:
> > @@ -14,26 +14,17 @@
> >
> >  """This module provides the HaaS service's public API.
> >
> > +Most of the HTTP logic is in haas.http, with a small number of exceptions.
> 
>    A pun? :)
> 
>    --
>    Reply to this email directly or [1]view it on GitHub.
> 
> References
> 
>    1. https://github.com/CCI-MOC/haas/pull/266/files#r17987471