=15648 ker Use wildcard in microkernel classpath

* scala-library.jar had changed name to scala-library-2.10.4.jar
* use wildcard to avoid same problem when scala-library version is changed
* the wilcard will only include jar files in the lib directory, and not the
  lib/akka directory, see 'Understanding class path wildcards'
  http://docs.oracle.com/javase/6/docs/technotes/tools/windows/classpath.html

(cherry picked from commit 996de05b44531bda517ef8ee274a34ad76e9716f)
Merge pull request #15660 from akka/wip-15648-classpath-master-patriknw

=15648 ker Use wildcard in microkernel classpath (for validation)