Checked items now work

This address issue #118.  The download and delete actions work as expected.  Internally, there are two new endpoints: resource/download GET and resource DELETE.  The download can actually get item, folder, user, and collection resources, and the delete can work on any model that has a remove method.
I'll change it to **kwargs.  The reason I added it to the base class was to
allow the generic remove to be used in the resource API without caring if
the target class knew what to do with progress.  I like the kwargs better,
since we don't have unused parameters, but we still allow arbitrary
parameters to be passed without raising an exception.

On Fri, Oct 17, 2014 at 5:38 PM, Zach Mullen <notifications@github.com>
wrote:

> In girder/models/model_base.py:
>
> > @@ -259,9 +259,11 @@ def increment(self, query, field, amount, **kwargs):
> >              '$inc': {field: amount}
> >          }, **kwargs)
> >
> > -    def remove(self, document):
> > +    def remove(self, document, progress=None):
>
> On second thought, maybe there's something to be said for having a uniform
> set of formal params across all the model types, so I'm OK with leaving
> this here. Maybe change it to **kwargs? Not sure on that.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/girder/girder/pull/398/files#r19045062>.
>