URIs escaped twice in URLScanner

The fix for WELD-834 can cause spaces to be escaped twice in an URL. This leads to errors like: Error handling file /var/lib/jenkins/jobs/Wicket%2520Weld/workspace/wicket-cdi-examples/target/classes

Notice how 'Wicket%20Weld' is escaped to 'Wicket%2520Weld'. https://github.com/papegaaij/wicket-cdi demonstrates the problem, clone the project in a directory with a space in the name, and run 'mvn install -Dwicket.version=1.5-RC5.1'.