Fixes for issues #4 and #8 + other stuff

New features and fixes:
 - simplification of configuration (merged and deleted config fragments)
 - added groups (issue #4)
 - added generic template for fair shares (issue #8)
 - moved non-used config files to files/examples
 - added desription of custom hacks
 - added documentation

Testing scheduled for Monday together with https://github.com/HEP-Puppet/arc_ce/pull/10