Fix missing perl XML::Simple dependency for sge_helper

[LincolnBryant]

The perl-XML-Simple package (as provided by yum on RH systems) doesn't exist on all clusters, so we've included the dependency within sge_helper via App::FatPacker[0]

[0]http://search.cpan.org/~mstrout/App-FatPacker-0.010007/lib/App/FatPacker.pm.

[brianhlin]

@edquist do you know anything about FatPacker?

[LincolnBryant]

@brianhlin @edquist happy to chat about this on slack as well- fatpacker basically inlines libraries into a perl script. alternatively i suppose you could put perl-XML-Simple separately in the blah tarball and include it in perl's @INC somewhere. we had this issue pop up at UCLA as I recall.