extmgr: Engine should start even if there is a wrong configuration of extension

Change-Id: Iac6b522eb8d5fc1f3993780e6c1f09f7e5046757
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1117397
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>