Merge pull request #483 from 4teamwork/lg-mail-download-copy

Use the same customized download view we use for documents for mails as well.
Fixed unicode decode bug in task overview.
Merge pull request #456 from 4teamwork/lk_fix_unicode_bug

Fixed unicode decode bug in task overview.
Changed German wording for value `unchecked` for both public_trial and archival_value:

"Noch nicht geprüft" -> "Nicht geprüft"