java_loxi: big refactoring and clean-up
java_gen/pre-written: fix exceptions
java_gen/U64: fix bug with treatment of usigned long values > Long.MAX_VALUE
java_gen: add Dummy OFFlowMod
java_gen/java_model: do not memoize enum.get_all_values (arg not hashable)
java_gen/java_type: support $version for string version of readOp/WriteOp
java-Gen/of_class: fix typo in reader
java_gen: change to maven build, remove lib directory
Make: add maven build for java
java_gen: skip table_mod for now
java_gen: clean filename handling
java_gen: remove unused methods
fix doc typo
Merge into master from pull request #38:
java_loxi: Major improvements / rewrite (https://github.com/floodlight/loxigen/pull/38)