tools: Added colon and space after new password prompt in engine-config

Added colon and space after new password prompt using:

  engine-config -s AdminPassword=interactive

Bug-Url: https://bugzilla.redhat.com/924603
Change-Id: I7abc9cba42e2407874c5022f81f40330fa7eba53
Signed-off-by: Martin Perina <mperina@redhat.com>