Added scanning for annotations.xml entries within maven dependencies

This patch provides scanning for annotations.xml files within the resolved dependencies for projects using the kotlin-maven-plugin, to avoid the need to explicitly list the paths for external annotations, and to allow third party libraries to package their own annotations.

This is tracked in http://youtrack.jetbrains.com/issue/KT-2765 (be able to discover annotations.xml files on the classpath from the maven plugin).