Updates for deploying to heroku

@jzoldak @cgoldberg  Please review. 

The biggest change is updating the mongo logic to use a URI from the environment instead of constructing one on its own.
Yea, pylons uses the older version.   Updating the version results in:

```
    from webob.multidict import UnicodeMultiDict
ImportError: cannot import name UnicodeMultiDict
```