fix permission for close completed sprint button, broken from releases merge
re #543 check user permissions when rendering backlog page menu

check for create_sprints permission on backlog menu
check for update_sprints permission when rendering sprint header
check for :update_stories permission when rendering backlog story
disable dragging stories if no update_stories permission, pass permissions into frontend
check for update/create tasks/impediments, refine create story, pass permissions into frontend
allow creating sprint when update_sprints is not set
do not handle usability in object partials

it does not improve security, is unneccessary load and can be handled in the frondend
reset cursor to default if story/task/sprint are not editable
Merge branch 'patrick/anonymous'