Bug 1051839 - Introducing the new es module for Elasticsearch 1.x.

@phrawzty This creates a fresh ``ConnectionContext`` class that is closer to what the other similar classes are. It also creates a new class called ``IndexCreator`` that takes care of all index creation logic. I took it out of the ``CrashStorage`` (where it lies in the current module) because I thought it did not really belonged there. I also needed to port some of the Super Search Fields list logic, that I also think should be separated from the main ``SuperSearch`` class, hence this new ``SuperSearchFields`` class. 

I think those 3 classes are all that are needed for the ``CrashStorage`` class. 
Concerned about using `es` as the default; prefer the legacy driver for now.