first draft on wcs link creation
added blank=True so admin fields aren't created as being required
Clear any orphan thumbnail before saving a new one
Delete the thumbnail on the resource base delete
Merge pull request #994 from simod/issue-993

Clear any orphan thumbnail before saving a new one
Better 500 error
Merge pull request #979 from simod/issue-973

set the layer public for the purpose of WCS link creation
Merge branch 'master' of github.com:GeoNode/geonode
Committed changelog