Commented-out classifier in components.xml (#35)

It turns out the Maven Source Plugin doesn't like it if the main
artifact has the empty string as its classifier.  It will fail printing
a warning saying "NOT adding sources to artifacts with classifier as
Maven only supports one classifier per artifact.  Current artifact
[xxxxx] has a [] classifier."  Apparently the classifier needs to be
`null`, which means leaving off the `classifier` tag altogether in
'components.xml'.  We comment-out the tag and include a reference to the
issue so we know why we did it.