Exclude non-required artifacts from the lib folder

This PR filters out .pom, sources and javadoc from projectDependencyArtifacts. The presence of the pom.xml would cause the project's jar file to be overwritten given that the xml and the jar have the same name sans extension. The javadoc and source are not required for running the project (which I presume is the motivation behind determining these artefacts).

This issue relates to https://github.com/playframework/playframework/issues/1564