[GEOS-6654] Refer to right Xlink XSD in WFS

In WFS 2.0 the wrong Xlink XSD was linked, instead of using the original
W3 Xlink, the old and deprecated OGC Xlink was used.  This change should
not impact further functionality of the WFS module.
Enable geojson geometry output in WPS
Merge branch 'wps-geojson-for-geometries'

Conflicts:
	src/extension/wps/wps-core/src/test/java/org/geoserver/wps/jts/GeometryProcessWPSTest.java
Merge pull request #764 from Geodan/GEOS-6654

[GEOS-6654] Refer to right Xlink XSD in WFS
Allow StyleGenerator to create style inside of a workspace.
Merge pull request #776 from jdeolive/style-gen-workspace

Allow StyleGenerator to create style inside of a workspace.
Added DataStoreFactoryInitializer for GeoPkg. Fixes GEOS-6708.
[GEOS-6707] SortBy property name validation breaks app-schema
Fixed jms-cluster artifactId in community release pom
Fixing some issues reported by Mark Jansen during a pull request review
Merge remote-tracking branch 'upstream/master'