File a copy of the mail in the dossier by default when sending documents from GEVER.
Merge pull request #376 from 4teamwork/lg-send-documents-file-mail-in-dossier

File a copy of the mail in the dossier by default when sending documents from GEVER
Add special public trial edit form, which allows editing the public trial information in a closed state.
Show public trial edit link if dossier is closed and the user has modify portal content permission in a open dossier state.
Hide public_trial and public_trial_statement in dossier and repositoryfolder.
Move find_parent_dossier method from opengerver.mail into opengever.base.utils.