CA-201311: Fix email alert text when trigger level is 0
CA-201311: Fix email alert text when trigger level is 0

Triggering at 0 is often used by QA to test things, and the
email generated under this condition (and only under this
condition) was just incorrect.

Signed-off-by: Jon Ludlam <e7e3380887a8f95cc9dc4f0d51dedc7e849a287a@citrix.com>

rafalmiel/xen-api,thomassa/xen-api,euanh/xen-api,euanh/xen-api,Frezzle/xen-api,euanh/xen-api,srowe/xen-api,jjd27/xen-api,rafalmiel/xen-api,jjd27/xen-api,thomassa/xen-api,Frezzle/xen-api,jjd27/xen-api,thomassa/xen-api,rafalmiel/xen-api,rafalmiel/xen-api,jjd27/xen-api,rafalmiel/xen-api,jjd27/xen-api,Frezzle/xen-api,euanh/xen-api,jjd27/xen-api,thomassa/xen-api,Frezzle/xen-api,srowe/xen-api,Frezzle/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,srowe/xen-api,thomassa/xen-api,rafalmiel/xen-api,euanh/xen-api,thomassa/xen-api