BibAuthorID: simplification and template fix in claims

* No need to define a 'pid_to_assign' variable.
* Changed 'other person' to 'another person'
  for consistency.

Signed-off-by: Artem Tsikiridis <artem.tsikiridis@cern.ch>
Reviewed-by: Gilles Louppe <gilles.louppe@cern.ch>