Fix SCMTriggerCause javadoc to deprecated constructor

http://javadoc.jenkins-ci.org/hudson/triggers/SCMTrigger.SCMTriggerCause.html
includes a deprecated constructor with an @{link } reference to the
preferred constructor.  That link is broken in the current javadoc.
This fixes the broken link.
Merge pull request #875 from MarkEWaite/javadoc-fixes-c

Fix SCMTriggerCause javadoc to deprecated constructor