Add script wicket user interface

The Community Script module does not currently have a Wicket User Interface. Adding a UI will make it much easier to add, update, and delete scripts.

Solves issue #GEOS-6483 (https://jira.codehaus.org/browse/GEOS-6483)
Good idea!  So, just to make sure I understand correctly, I should move everything in the org.geoserver.script.web package into a web module in the script community module?