Fix stage/dist classpath: Application jar should be the first in start script

When using dist or stage commands the generated start script contains a classpath where the application jar is the last (for dist) or it's part of a file expansion pattern (-cp "foo/*") which is often evaluated alphabetically. Thus application provided classpath resources like logger.xml, ehcache.xml or messages may or may not be used depending on other
jars in the classpath.

This commit puts the application jar(s) as the first ones in the classpath, so that resources provided by the application are definitely used.

A related thread on the mailing list: https://groups.google.com/forum/#!topic/play-framework/ChcD5ad5fQg