fix jquery namespace issues, update to 1.7.2-ui-1.8.21

avoid loading of backlogs jquery on redmine views for redmine >= 2.1

remove is_backlogs_view, ise is_a? RbApplicationController

syntax
drop handling: select only sortables for enable/disable for jquery-ui-1.9
fix burndown and release jquery namespacing
Merge branch 'ui/jquery-17'