Send Build Notifications to Jenkins Admins

Send Build Notifications to Jenkins Admins

Given the number of jobs in OPNFV there isn't an easy way to discover
when there is an issue affecting a large number of jobs without looking
into individual job logs.

By sending out email notifications on failed builds (using the email-ext
plugin), we will have insight into causes for large sets of job
failures, and also be able to identify non-job specific issues.

This macro still needs to be added to jobs that already have publishers
set, but by just adding it to defaults it should cover about half of all
current jobs.

JIRA: RELENG-257

Change-Id: I9d55bdd929a60004a16fa3c21bf1f7069f8786db
Signed-off-by: Trevor Bramwell <tbramwell@linuxfoundation.org>