fix and test sharing pages
fix and test assigning tasks - fixes #7867
fix saving the page visit timestamp - fixes 7883

also use it for the (new) or (modified) indicators in the task page
no more need to backport from rails 3.1 :)
translation and ui tweaks for task_list - fixes 7866
Merge pull request #68 from azul/bugfix/task-list-issues

Bugfix/task list issues