BibAuthorID: single profile when moving signatures

* Attributes signatures re-assigned by a curator
  to a single profile. So far, one new pid was
  created per paper.

Signed-off-by: Artem Tsikiridis <artem.tsikiridis@cern.ch>
BibAuthorID: no early creation of person, etc.

* fixes issues reported in code review.
  The create_person should not be called
  before actually confirming.
* CREATE_PERSON not the default action
  in construct_operation.

Singed-off-by: Artem Tsikiridis <artem.tsikiridis@cern.ch>
BibAuthorID: always create a profile, rabbit cleanup

* When reassigning signatures, to avoid huge
  concurrency problems by two users using
  the same author id in the same time, it is
  safer to always create a pid and clean up
  by rabbit.
* Tuned remove_empty_authors to actually
  remove these authors.

Signed-off-by: Artem Tsikiridis <artem.tsikiridis@cern.ch>