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)
DDF-894 Added propertyIsNull support to the SolrFilterDelegate

-kind of odd to get this to work.  First you come in without a field type so we have to do so using the getAnonymousField() method.  Than we have to use the negative queries to actually get the results we need. (*:* -fieldName:[* TO *]) is the magic sause to get this to work.  For details on how this works, visit the url below.
-http://stackoverflow.com/questions/17044661/how-to-filter-search-by-values-that-are-not-available/17045097#17045097
Merge pull request #38 from McLucas/feature/DDF-894

DDF-894 Added propertyIsNull support to the SolrFilterDelegate
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
DDF-920 Federated sources should display correct status/availablity.
* Added a status model and polling to display the current status of all federated sources.