EPIC: toshi-hazard-store Revision 4

[chrisdicaprio]

Improvements to toshi-hazard-store to simply hazard pipeline and facilitate 3rd party use:

• feature: db_adapter - use alternate database(s) for primary storage.  #53
• remove toshiAPI IDs from key values for realizations. They can be continue to be stored, but should not be necessary to lookup realizations
• use hash of oq config as part of key value for realizations. This can be used to ensure that all realizations that go into a aggregate (THP) calculation use the same oq config settings and same oq version
• Migration tool to copy / move curves as needed #60