Adds frequency images/dicts to hdf5 file

Also added some placeholder versioning - right now, if you've already got an older .h5 file, it just squawk about unsupported version so you'll have to delete and recreate your .h5 files. I don't think it's worth implementing automatic upgrading of the hydropick hdf5 files just yet since we're still in dev mode and it doesn't take *too* long to regenerate files.

...and bumped required pytables version to 3.0.0 mostly for api reasons - I was working off the 3.0.0 docs, if 3.0.0 is a problem I can revert to the tables.oldSchoolAPI