Automatically initialise elasticsearch.

Charmstore will now automatically initialise elasticsearch when starting up.
This ensures that elasticsearch will always have the index and mapping
configuration required for correct operation.
Merge pull request #231 from mhilton/automatic-elasticsearch-sync

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.