java_gen: fix documentation in OFGroup

lots of '...port' still lef tin there
java_gen: correctly handle of_action 64-bit alignment

of_action is different from oxm in that it is 64 bit aligned,
but the alignment is contained in the length field.

Added optional parameter "length_includes_align" to the input files
to handle this situation.
java_gen: support glob based test_data files

enables us to have more than on unit test per class.

Additional tests follow the pattern:
${class_name}__${suffix}.data
test_data: add java stanzas to action tests

and rename them to follow the glob conventions for java_gen
java_gen: fix alignment on read of messages that are internally aligned

I.e., if the alignment is contained in the length field
java_gen unit tests: make sure the entire message is consumed on read
Merge into master from pull request #102:
Java gen: fix alignment for action set_field, add java_gen unit tests for actions (https://github.com/floodlight/loxigen/pull/102)