Automatically initialise elasticsearch.

Charmstore will now automatically initialise elasticsearch when starting up.
This ensures that elasticsearch will always have the correct index and mapping
configuration required for correct operation.
Yes, but these tests were for the PutDocument function on the elasticsearch.Index data type which I have removed because the application is now maintaining it's own indexes. The (almost identical) test functions for the PutDocumentVersion function on the Database data type are still present.