Fixes in AccessClassLoader and MethodAccess

Includes:

- Fix #21 - Solve PermGen memory leak in AccessClassLoader
- Fix #17 - MethodAccess now supports accessing interface types (uses INVOKEINTERFACE instead of INVOKEVIRTUAL)
- Fix #11 - Added a more specific MethodAccess.invoke(Object, String, Class[], Object...)
- Improved MethodAccess.invoke(Object, String, Object...)
- Fix #16 - Fixed the regression in the commited fix: ConstructorAccess.get must throw RuntimeException if the no-args constructor is private