bump jquery-rails and jquery-ui-rails versions
can_stock? has been refactored into can_supply?

Fixes #4291
Use jquery-rails 3.1.0 in frontend
Check if spree route proxy responds to root_path

Some stores may not define a root_path under spree engine. Currently
only spree_frontend component does that.
Add product with track_inventory false via backend

Fixes #4309
Bonobos additions to 2-1-stable