Bug 1051839 - Introduced elasticsearch-py, used it for all bulk indexing.

@phrawzty How is that as a very small first step? It only touches tests and scripts, nothing that Socorro actually runs, so it's pretty safe. 

Maybe we can work iteratively from there. Also, I'd like us to start using ``ConnectionContext.get_connection`` systematically to get a new connection to Elasticsearch from now on. I believe it will make things a bit cleaner and easier to maintain. 
Comments are _le_ good, so I added 3 of them in this file.