Fix issue when uploading files with firefox over the Document AddForm.

Added temporary monkeypatch to ignore mimetypes sent by the browser (see https://github.com/plone/plone.formwidget.namedfile/pull/9):
We can't include the fix with the newests version (1.0.11), because this versions need also the newest z3c.form (see https://github.com/plone/plone.formwidget.namedfile/pull/10).

With the planed update to Plone 4.3 this monkeypatch should be removed.
Merge pull request #616 from 4teamwork/pg_formwidget_namedfile_monkeypath

Fix issue when uploading files with firefox over the Document AddForm
Fix an unicode issue while syncing document filename and title.

Fixes #584.
Merge pull request #608 from 4teamwork/deif-fix-unicode-filename

Fix an unicode issue while syncing document filename and title.
Don't create dicts but use real objects as temporary participants.

This solves an issue with filtering for the participants tab. Fixes #583.