open: Change file() to open()

Update file calls to open calls due to file's deprecation.

This patch does not convert all calls, more patches will follow.

Change-Id: I80007044be1c648ebb668704731eae8b83366025
Relates-To: https://bugzilla.redhat.com/show_bug.cgi?id=1128715
Signed-off-by: Dima Kuznetsov <dkuznets@redhat.com>
Signed-off-by: Yeela Kaplan <ykaplan@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/26776
Reviewed-by: Dan Kenigsberg <danken@redhat.com>