Output-wicketpaths init parameter should be a context parameter

CMS7-3951 added the option to turn on wicketpaths for html elements to improve testability of the CMS Application.

This setting is currently a servlet init parameter in the web.xml of the CMS, which makes it hard to turn it off on production and enable it on acceptance/test/development.

There should be a context parameter with the same name and behavior so that this parameter can be changes from the server/context.xml. For backwards compatibility the original servlet init parameter will still be supported.