DDF-868 Default enabled source to the newly created configuration.
* New source configurations are automatically enabled rather than defaulting to a 'disabled' state
* Configuration save logic rewritten to wait for any disable (configuration) calls to finish before issuing a model refresh event. (+1 squashed commits)
Merge pull request #41 from jeremyglasser/rebase/DDF-868-Default-to-created-source

DDF-868 Default enabled source to the newly created configuration.
DDF-924 added the ability to populate the thumbnail portion of a metacard via the tika transformer and updated the content create response to json
DDF-828: Added comment about programmatic service registration and updated service desc