backend: fix typo when InstallVdsCommand fails

1. s/enging/engine
2. change path of host-deploy log to correct path

Change-Id: If0d985eaf8a3d2060b53f4c031e8a49e74799cbf
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=923693
Signed-off-by: Ohad Basan <obasan@redhat.com>