CAT-SOOP as LTI Consumer #34

We should set things up so that catsoop can act not only as an LTI producer (providing problems for other things), but also as a consumer (eating problems from other places). I wonder if it makes sense to set this up as a question type.

Maybe the global context could have information about the various LTI producers that we expect to talk to, and then an instance of the question could refer to one of those things as well as the details of the particular resource we want to include. So maybe something like

csq_lti_producers = {
   'name': 'mitx',
   ...: ...,
}

and then

<question lti>
csq_producer = 'mitx'
csq_resource = '/path/to/particular/question'
csq_npoints = 1
</question>

or something like that.