Added missing mediafile projector stylefile for pdf.js presentation.
Fixed permission error in some widgets.

Fixed agenda item widget, assignment widget, motion widget, participant user widget and participant group widget. Fixed #1279.
Changed permission system for config pages.

Config pages are now only available for users with permission 'config.can_manage'. Fixed #1159.
Fixed English strings concerning agenda items and organizational items and their relation. Fixed #1271.
Changed some docstrings.
Fixed error when creating an assignment poll. Fixed #1203.
Merge pull request #1273 from normanjaeckel/Docstrings

Changed some docstrings.
Merge pull request #1277 from emanuelschuetze/fix-mediafileprojector

Added missing mediafile projector stylefile for pdf.js presentation.
Merge pull request #1281 from normanjaeckel/AssignmentPollBug

Fixed error when creating an assignment poll. Fixed #1203.
Merge pull request #1282 from normanjaeckel/FixWidgets

Fixed permission error in some widgets.
Merge pull request #1284 from normanjaeckel/RefactorConfig

Changed permission system for config pages.
Merge pull request #1283 from normanjaeckel/FixEnglishString

Fixed English strings concerning agenda items and organizational items a...