MBS-6218: don't try to merge genders when merging into an artist of type 'group'
MBS-6218: add test
MBS-6218: move group type to a constant
Return a 400 error if a user tries to submit edits using /ws/2 without a confirmed email address.
Merge branch 'mbs-6218' into beta

* mbs-6218:
  MBS-6218: move group type to a constant
  MBS-6218: add test
  MBS-6218: don't try to merge genders when merging into an artist of type 'group'
Merge branch 'confirmed-email-ws2' into beta

* confirmed-email-ws2:
  Return a 400 error if a user tries to submit edits using /ws/2 without a confirmed email address.