Nucivic nucivi internal issue 25 viz datastore connection

NuCivic/nucivic-internal#25

Consuming resources from dkan datastore instead an static object.
### Acepptance test
* git pull
* Add a resource to datastore
* Create a new visualization with this resource.
* Resources now shoud load progressively by ajax.

Notes: The data could be loaded more quickly than the browser could render it. In this case some progress notifications could be missed.