Catch KeyboardInterrupt

When a user Ctrl-C's the client, this will cause a short message to
be printed rather than an ugly backtrace.

This will not catch all instances of this (can still Ctrl-C before
reaching this code, etc.), but it should catch most of them, and those
for long-running sessions.

The specific message was chosen to match one recently added to the
glance client.

Change-Id: Ib748835ad1f94fb901b4941dc5e3797b719e197f
Add debug option processing to run_tests

This just adds -d|--debug option so you can debug
using tools like pdb again and to get extra output
from the tests.

Change-Id: Icebc17a1575e17cfd9597581546dca4732b9a8ef
Merge "Catch KeyboardInterrupt"