Add preliminary support for pulling in arrays for fields

We're seeing the values in lumberjack.conf get moved around occasionally by puppet.  After doing some research it sounds like hashes will not always keep the order for each pair.  Arrays are supposed to always keep their order, so this adds the ability to enter the 'fields' values using an array.  Later, in files.pp puppet will use the hash() function from stdlib to convert the array back to a hash for the template to use.  This seems to work, but I don't know if it could still potentially get shifted around by puppet/ruby.  The ideal solution would be to pass the array all the way to the template, but that would require quite a bit more time for a ruby novice like me to do.