Avoid using Pathname to compute relative paths in spout

Merge inadvertently changed inherited method to once again use
Pathname to compute relative paths. This change once more allows
the code to work either in a jar context, or a .rb file on
the filesystem.

lib/red_storm/dsl/spout.rb

@@ -162,7 +162,7 @@ module RedStorm
       # below non-dry see Bolt class
       def self.inherited(subclass)
         path = (caller.first.to_s =~ /^(.+):\d+.*$/) ? $1 : raise(SpoutError, "unable to extract base topology class path from #{caller.first.inspect}")
-        subclass.base_class_path = Pathname.new(path).relative_path_from(Pathname.new(RedStorm::BASE_PATH)).to_s
+        subclass.base_class_path = File.expand_path(path)
       end
 
       def self.base_class_path=(path)