Bugfix: Build output directory was not added to classpath if it contained TLD files

Whenever any directory on the classpath contains TLD files, the directory itself would not be added to the classpath. This also applies to the build output directoy, which seems not intended (https://jira.codehaus.org/browse/MJSPC-60).

This has been fixed by checking if the build output directory was a) part of the classpathElements and b) not yet in the classpath list. If both applies, it is added to the classpath.