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
This and SignaturesByBugs are the two classes that were changed to use the dataservice defined in `socorro.external.postgresql.bugs_service`