Raise exceptions when no entrypoint, macro or template found

When generating XML and no component is found for the given yaml entry
whether it is a JJB module, macro or job template, raise an exception
instead of silently continuing by not generating XML and requiring the
user to check the results.

Change-Id: Icd4b1fae123c8bbb4d8af7aa14522251cd9cf8d5
Merge "Raise exceptions when no entrypoint, macro or template found"