Fixes and features

 - merged manifests/config/* with manifests/config.pp
 - added custom fixes
 - added plugin for default RTE (thanks Andrew!) - issue HEP-Puppet/arc_ce/#8
 - added runtime environments (GLITE/PROXY)
 - added a bit of documentation
 - updated the nordugrid repository from 13.02 to 13.11

This pull request is not yet ready to merge, please wait until I can test it.