History API: show: add importable, username_and_slug to returned attributes, update: 1) allow setting importable and published, 2) published automatically makes a history importable, 3) in both cases slug is automatically set set_as_current: now correctly uses the HTTP method PUT (not POST), HDA API: all: histories that are importable and/or published now allow GET'ing the contents properly, create: you can now copy HDAs into your histories if the HDA and it's history are accessible
History/HDA API: begin normalizing exceptions and return codes; Browser testing: update and expand history/hda testing, add importable/published permissions testing, transfer upload functions to api module
merge