Bug 24819: Allow the librarian to choose a patron when entering a purchase suggestion

Bug 24819: Allow the librarian to choose a patron when entering a purchase suggestion

Sometimes librarians are creating purchase suggestions that came from patrons
which didn't use the opac (but sent an email, or told the librarian verbally...)

This patch allows the librarian to change the creator of the purchase suggestion
when entering it.

This way, the patron will be able to receive notifications during the purchase
suggestion workflow.

Test plan:

 - Apply the patch

 - Check that you can change the default creator of the purchase suggestion when
   creating a new suggestion by clicking on 'Set to patron'
   (Home > Acquisitions > Suggestions management > New purchase suggestion)

 - Check that you can also change the creator of the purchase suggestion when
   editing an existing suggestion

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>