MERGE CAUTIOUSLY Bug1097988 dataservices in api


This patch implements a dataservice app that loads configuration and objects with configman and points two crashstats.models classes (Bugs and SignaturesByBugs) at those objects.

Before we merge, things to sort out on stage: 

* Are we stowing all our *.ini config on webapp servers?
* Any special config needed for secrets?
* What's our process for updating local.py? (required for this change)

I removed two tests for non-caching.. probably need to resurrect those or not... :D
The reason for not putting the URL in the service, is that we're letting this be managed centrally in Django. If we support multiple dataservice frontends (like a Flask app for example) I could see us moving the URL here. Until then, seems like duplication for no good reason.