add rack-mini-profiler to Gemfile

also require latest Arbre to work around gregbell/arbre#16
Add spec revealing error in has_many sortable behaviour: Unsaved records are lost when reorder is called on children.
Fix has_many sortable error: Unsaved records are not displayed.
Merge pull request #2747 from kirel/master+has_many-sortable-fix

has_many sortable unsaved records fix
Add access denied local to zh-CN
CSS cleanup
let the scopes UL overflow
float scopes to the right when they overflow

IMO this looks much better than having them overflow directly beneath
the Batch Actions button
remove gem version requirements

all except Capybara :/
brings back the resource mismatch error

resolves #2728
Merge pull request #2746 from seanlinsley/ui/2743-scope-overflow

Properly handle index scopes overflow
Fix for box-shadow deprecation warning
Merge pull request #2760 from arturtr/patch-1

Fix for box-shadow deprecation warning
#2762: remove list style on scopes
Improve 'ja' translations