Add classification behavior to mails.
Merge pull request #359 from 4teamwork/mle-public_trial_classification

Classification behavior on mail
Show classification infos on document overview tab.
Refactor overview tests (use ftw.testbrowser).
Add overview tab for mail (Inherited from document overview tab).
Merge pull request #367 from 4teamwork/mle-public_trial_show_on_overview

Show public trial informations on overview tab (document and mail)
File a copy of the mail in the dossier by default when sending documents from GEVER.