drop junitext junk to remove a project dependency which is not in Maven central.

https://code.google.com/p/junit-ext/ is dead and JUnit now provides Assume.assumeThat which can/should be used instead.

URLMatchersTest includes example of how assumeThat can work.
URLMatchersTest does not need to extend TestSupport
Merge pull request #19 from sonatype/drop-junit-ext

drop junitext to remove a project dependency which is not in Maven Central