support pluggable url mangling

Url mangling is useful when integrating with geoserver. If a proxy url
is set, that's the one that should be used during url generation.

Conflicts:

	geowebcache/web/src/main/webapp/WEB-INF/geowebcache-core-context.xml
Moved contextPath extraction to method on ServletUtils
Extend URL mangling to WMS GetCapabilities

Conflicts:

	geowebcache/wms/src/test/java/org/geowebcache/service/wms/WMSServiceTest.java
Extent URL Mangling to WMTS GetCapabilities
Detect if GWC is embeded within a parent servlet and include the context path of the parent in the base URL for mangling purposes.
Fix base path for URL mangling in Rest
Restore old constructor signatures and add defaults for mangler related parameters to restore backward compatibility.
Merge pull request #152 from smithkm/url-mangling-master

Pluggable URL Mangling
Fix typo in app context
Expose the monitored quota store
Improve the design of the lock provider, makes it easier to use, less error prone, and easier to wrap in a thread safe manner by a configurable lock provider (one where the inner lock provided can be changed at runtime
Fix typo
Clean up Exception usage, make it easier to integrate this code in GeoServer
Avoid trying to delete the tiles of a layer called 'null' (which is really the global quota one)
The chosen quota store was not set when copying the configuration from another bean
Add a facility to reload the disk quota config
Added a method to check the jdbc configuration validity
Updated GeoTools and Spring dependencies 9-SNAPSHOT and 3.1.1.RELEASE respectively, matching the versions in GeoServer master.
Updated jUnit to 4.10 with additional Hamcrest matchers
Merge pull request #160 from smithkm/master

Updated libraries