Use the correct classpath seperator

I guess I'd never tested having more than a single jar file when
compiling scala code.  The problem is now fixed.
Set scala classpath when linking

I'm not entirely sure if this is necessary or if it ends up baked into
the class files somehow, but I think it's a safe bet to actually set
it when building the jar that's inside the self-extracting executable
I use to ship scala binaries.