Release 0.2.0

NB: This release is not backwards compatible!

• requires JavaBridge 1.0.9 at least
• moved from Java-like get/set (getIndex() and setIndex(int)) to nicer Python properties
• using Python properties (also only read-only ones) wherevere possible
• added weka.core.version for accessing the Weka version currently in use
• added jwrapper and jclasswrapper methods to JavaObject class (the mother of all objects in python-weka-wrapper)
  to allow generic access to an object's methods: http://pythonhosted.org//javabridge/highlevel.html#wrapping-java-objects-using-reflection
• added convenience methods class_is_last() and class_is_first() to weka.core.Instances class
• added convenience methods delete_last_attribute() and delete_first_attribute() to weka.core.Instances class