#73 better junit integration with CodeNarc runner

[Hamlet D'Arcy]

We in codenarc have this "RunCodeNarcAgainstSelf" unit test that runs CodeNarc against our own code.
We should clean this up and make it an abstract test case so that users could easily do the same against their own codebase from JUnit.
It would allow people to add the .jar file and play with codenarc without configuring builds, etc.

The runner currently uses Ant and we should modify this to not use ant.