use File::PATH_SEPARATOR for classpath when constructing classpaths in Rakefile
use File::PATH_SEPARATOR for classpath when constructing classpaths in Rakefile

':' isn't the path separator on windows, so hardcoding the path separator leads to an inability to build on windows. :(

This fixes it.

uujava/mirah,mirah/mirah,felixvf/mirah,felixvf/mirah,mirah/mirah,felixvf/mirah,uujava/mirah,KeenS/mirah,uujava/mirah,mirah/mirah,KeenS/mirah,KeenS/mirah,felixvf/mirah,uujava/mirah,uujava/mirah,mirah/mirah,KeenS/mirah