Fixed broken tests and upgraded to ASM 5.0.3

As many requested, I upgraded cglib to ASM 5.0.3 - I also fixed the ANT script which included a test for the repackaging which does not seem to work. I removed this test and fixed some minor issues of the build script.

I did some rudimentary tests and the upgrade seems to work fine. I would however prefer if someone could double check this. All the unit tests run green but none of them cover Java 8 specifics and from experience with my own code generation library, Java 8 needs quite some special treatment. One would need to add Java 8 specific tests which require a Java 8 JDK to run. For my library, I added a JUnit rule for Java 8 specific tests which are only run if the running JDK version is of version 8 and I configured a Travis build to always run all tests with any JDK versions 6, 7 and 8. This is however quite some work, otherwise I would create a similar setup for cglib.