[SHARE-1058] Reingestion

[aaxelb]

• Add IngestScheduler to help with creating/running IngestJobs
  • schedule(suid, ...): Create/get an ingest job for the latest raw datum for the given suid
  • reingest(suid): schedule an ingest job, then run it synchronously
  • reingest_async(suid): schedule an ingest job, then spawn an ingest task for it
  • bulk_reingest(suid_qs): like reingest_async, but optimized for lots of suids from a queryset
• Add "Reingest" action to Suid admin page
  • While mucking about in the admin, make read-only foreign keys into links
• Update sharectl ingest
  • Remove --all flag
  • Add --suids, to allow reingesting suids by id

https://openscience.atlassian.net/browse/SHARE-1058

[coveralls]

Coverage increased (+0.4%) to 79.275% when pulling 3de99972e717aa3dad037071200715eb2a6048d2 on aaxelb:share-1058--reingestion into cbf7ce5cd3294193e8848d76945668ea8be164d8 on CenterForOpenScience:develop.