Add slash and escape keyboard shortcuts for opening and closing the nav.

Change-Id: I83984a8f8887d92d99359609381f936d274373d1
Merge "Add slash and escape keyboard shortcuts for opening and closing the nav."
cammount: don't require a mount dir; add --open flag

Change-Id: I87c280b333a1ee9445b74e3ee1c87f6c08931ef3