update
Fixing issue with STI and bulk import

  - When reindexing, the Index.import method checks the type of the
    first record and uses that for all records indexed.
  - Send records through a group_by filter first and then index them in
    groups by type
Merge branch 'fix_sti_clobbering' into feature/add_scoping_to_results

* fix_sti_clobbering:
  Fixing issue with STI and bulk import