Updates geonode_authorize_layer procedure to new data schema (abstract inheritance)

there is no layer.id since layer inherits from resourcebase in the new schema. ditto for layer.owner_id.
sanity check for map download request

allow for both readme and title to coexist, don't make author
a required field

refs geonode/geonode#1257
Fixes https://github.com/GeoNode/geonode/issues/677

Thanks @ischneider
Merge pull request #12 from cspanring/patch-1

Updates geonode_authorize_layer procedure to new data schema (abstract inheritance)
Merge branch 'master' of github.com:GeoNode/geoserver-geonode-ext into 2.4.x
Merge pull request #13 from GeoNode/fix-map-download-name

sanity check for map download request
Fixes https://github.com/GeoNode/geonode/issues/1261
Use 'layers' as the apps_label when looking up layer permissions.
Update the importer dependencies to reflect the new groupid.
Merge pull request #17 from garnertb/importer-update

Update the importer dependencies to reflect the new groupid.
Merge commit 'a221067c97f3b965f198a6fe733ca20e6df745a8'
Replace the username variable with user_name.
Update geonode_authorize_layer.sql to work with groups.
Minor improvements.
Merge pull request #18 from garnertb/group_support

Add group support.
Fix a bug that prevented anonymous roles from propagating up to registered users.

*plpgsql array indexing starts at 1 not 0.
Move the generic read-only logic to come after all read-write lookups.
Use group-* for group permission hits vs gr-* which is also used for generic roles.
Merge pull request #19 from garnertb/geonode_authorize_layer_bugs

Small fixes for geonode_authorize_layer bugs.
Log URL also