Endpoints for Creating and Deleting Datastores

[DanielElisenberg]

Endpoints for Creating and Deleting Datastores

Now that each datastore-api support multitenancy we can move the code for setting up the datastores out of the initialiser and into the api itself to allow for programatic creation and deletion of datastores.
Consider implementing soft deleting the datastores to allow for some mitigation of wrongful deletion.

Creation and deletion should be done by POSTing a creation json to /datastores/ or DELETEing at /datastores/