WFS Cascaded Stored Query support (rebased and squashed)

Add WFS-NG plugin

Provided dependency: gs-main

Add wfs-ng profile

Propagate spring application context to the XStreamPersisterFactory instance.

XStream initializers for wfs-ng extension configuration

Stored query id is no longer part of the configuration, eliminate it from the tests

Add wfs-ng

Update copyright notices

Switch feature source metadata maps to <String,Object> from <String,Serializable>

Pass feature source metadata as ConfiguraionMetadataKeys in query hints.

Reverted hack that was no longer needed after previous merge

Add alias for stored query parameter blocking mapping

First pass of stored query configuration. Creating new feature types works.

Separate stored query selection to new stored query page

UI for configuring stored query parameters

Working on the Stored Query configuration model

Add basic validation for cascaded stored query configuration

Add missing copyright clauses

Refactoring needed for merging of pluggable wfs vs wfs-ng

Fix import packages

Remove duplicate test dependency

Move XStreamPersister to wfs module and remove the now empty wfs-ng extension

Cleanup of unnecessary changes

Remove auto-generated TODOs

Fix issues from rebase

Add missing license

Add basic javadoc comment for class

Remove duplicate dependency to gt-wfs-ng (merge artifact)

Remove release/ext-wfs-ng.xml, which was a leftover from old work

Add one-line javadocs

Add copyright headers

Added copyright header

Add spring configuration that went missing during rebase

Add hashcode and equals for StoredQueryParameterAttribute
Add GeoServerFeatureSource.Settings class
Change feature source metadata from Map<String, Object> to MetadataMap so it's more clear what metadata is required here
Expand comment for code that adds feature source metadata into query hints
Add temporary name support for CascadedStoredQueryCallback
Safely copy metadata into query hints

Illegal hints are logged.
Merge remote-tracking branch 'upstream/master'