Add modify deadline translations.
Fix existing translations, add missing msgids to plone.pot file.
Add transition, dispatch to correct view. update translations.
Add cancel button to modify deadline form.
Remove unused `create-successor-task` action.
Add modify-deadline transition to task workflow.
Update transition handler for modify-deadline.
Remove modify-deadline content action from task.
Update re-used upgrade-step description.
Update button styles, make sure save is green.
Cleanup plone.pot, remove duplicate newlines.
Pass responsible client (current org-unit) when creating sub-tasks.

Fixes #381.
Add delegate transition to workflow and transition controller.
Remove delegate action from task type.
Update deadline modification description, show modification details.
Fix error message, use admin-unit id.
Use correct content-type when returning 'OK' responses.
Fix unicode-decode error when syncing tasks.
Merge pull request #382 from 4teamwork/deif-actionmenu-viewlet

Add delegate and modify deadline to the actionmenu viewlet