v2.6.0

(cmdln) ddrimport command using Click.
(cmdln) ddrexport command using Click.
(cmdln) New vocabs retrieval code
(cmdln) batch,docstore: Update to support new vocabs retrieval code.
(defs) entity/segment; Update to support new vocabs retrieval code.
(local) settings,search,views: Update to support new vocabs retrieval code.
(cmdln) batch: Handle new files that don't yet have their own IDs.
(cmdln) batch,csvfile: Don't crash if new files have duplicate parent IDs.
(cmdln) idservice: Allow for alternate IDSERVICE_API_BASE (for testing).
(cmdln) config: edits to idservice-related configs.
(cmdln) idexport: Only export IDs that idservice can ingest.
(cmdln) Retrieve segment file metadata from Internet Archive during indexing for ddrpublic.
(cmdln) models: More sophisticated code for selecting entity signature.
(cmdln) models: Specify entity/segment media (img,video,audio) when indexing for ddrpublic.
(cmdln) models: Only make entity dir if necessary
(cmdln) test.sh: save coverage data to /tmp/ instead of project dir.
(cmdln) updated many unit tests
(local) Makefile: task for running ddr-cmdln unit tests
(local) models: rest_framework URL reverse function.
(cmdln) docstore: more feedback for bad JSON files.