Fixed mail download for mails with already CRLF.
Merge pull request #653 from 4teamwork/pg_mail_download_fix

Fixed mail download for mails with already CRLF.
Forwarding Transitioncontroller: Fixed assign_to_dossier check.

Right now the `assign_to_dossier` (etc.) guard does not work correctly, when a forwarding has a responsible user without agency_group belonging. This results that the responsible user of the forwarding can't do any action.

This commit solves this problem.