Catch CTRL+C and don't exit

Previous behavior was to keep the TUI running when CTRL+C was
pressed. Reintroduce that behavior.

Change-Id: I2803b010165996ea17a7da69e60e7c82cf218243
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1065848
Signed-off-by: Ryan Barry <rbarry@redhat.com>