Provide CRUD for Datasources

The agent needs to provide the facilities to create / read / update / delete datasources (and in the future other AS-resources) in standalone (and later domain) mode.

For creation, the agent can assume that the jdbc driver is already part of the system. If it does not exist, an exception may be raised to the Hawkular-server/UI.

Deletion needs to check if the datasource is still in use.