Non-issue classification types shouldn't be included in migration issues report

From Marc:

• The "Transformed to: JBoss application descriptor" items are listed as "optional issues". I my opinion, generated files should always be combined with another rule explaining what and why something has been generated ... and should not be visible in the overview.

This goes back to how we overload classifications with some being issue types and others being used to tag information to a file. Not sure what action we want to take on this but it's a reasonable point that it's strange to list things that aren't issues in a "Migration Issues" report.

This also applies to classifications like "WSDL Definition", "Maven POM", "Web XML", and so on.