engine: fix typo

Wair for launch -> Wait for launch

Change-Id: I99c62ee25ff60328b1a6510a39374a50694ae610
Bug-Url: https://bugzilla.redhat.com/1013998
Bug-Url: https://bugzilla.redhat.com/1005689
Signed-off-by: Frantisek Kobzik <fkobzik@redhat.com>
Signed-off-by: Tomas Jelinek <tjelinek@redhat.com>