Fix an NPE thrown when the user dropped a source from the geocatalog on the map
Adds a close after the open so that the needed DataSource is
instanciated and we're still sure we won't have less calls to close than
calls to open because of this method.
We're not really checking that edid is open. we want to know if its datasource is null or not.
Merge pull request #417 from agueganno/fix-414

About 414 - NPE when dragging a source on the Map.