autopep8
Refs #9813 retrieve ddcGeo and ddcTime from the sparql query, clean up

I removed some conversion code in opac.py. This seems to have been
used some time in the past to convert from an internal code, possibly
for translation. Now it only filters out ddcSubject codes, but this is
currently handled on the client side anyway:

syslabcom/recensio.theme/recensio/theme/skins/recensio_theme/oai.js
Tidy up: sort imports, retval->returnval, remove bogus/misleading comments

Although returnval is also a silly variable name, retval is a pdb
keyword.
Refs #9813 Add ddcGeo and ddcTime lookups, cache network queries for 6 hours
Refs #9813 Add "t1:" prefix to ddcTime, to match the form option values
Remove commented pdb
Get some sparql tests running by default, but move most to layer 100