docker: Use cockpit.defer() instead of $.Deferred
docker: Use cockpit.defer() instead of $.Deferred

Cockpit's promises are a superset of jQuery's, so this doesn't change
any behavior. Changing this now because we're about to change
show_modal_dialog() to work with standard JS promises, which
unfortunately in turn breaks jQuery promises.

Leaving other uses of $.Deferred untouched.

stefwalter/cockpit,cockpituous/cockpit,cockpit-project/cockpit,garrett/cockpit,martinpitt/cockpit,andreasn/cockpit,cockpituous/cockpit,cockpituous/cockpit,deryni/cockpit,martinpitt/cockpit,mvollmer/cockpit,SotolitoLabs/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,andreasn/cockpit,mareklibra/cockpit,deryni/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,SotolitoLabs/cockpit,SotolitoLabs/cockpit,SotolitoLabs/cockpit,andreasn/cockpit,mareklibra/cockpit,andreasn/cockpit,martinpitt/cockpit,andreasn/cockpit,mareklibra/cockpit,garrett/cockpit,deryni/cockpit,garrett/cockpit,garrett/cockpit,deryni/cockpit,deryni/cockpit,cockpit-project/cockpit,stefwalter/cockpit,SotolitoLabs/cockpit,SotolitoLabs/cockpit,cockpit-project/cockpit,stefwalter/cockpit,mareklibra/cockpit,mareklibra/cockpit,mvollmer/cockpit,mvollmer/cockpit,martinpitt/cockpit,stefwalter/cockpit,cockpituous/cockpit,cockpit-project/cockpit,SotolitoLabs/cockpit,mvollmer/cockpit,stefwalter/cockpit,cockpituous/cockpit,andreasn/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,garrett/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,deryni/cockpit,cockpit-project/cockpit,stefwalter/cockpit,stefwalter/cockpit,mareklibra/cockpit,deryni/cockpit,andreasn/cockpit,mareklibra/cockpit