def find_gem_file(rubygem, file)
      begin gem(rubygem); rescue Exception; end
      (dir = $:.find {|e| File.exist?(File.join(e, file)) }) && File.join(dir, file)
    end
def find_gem_file(rubygem, file)
      begin gem(rubygem); rescue Exception; end
      (dir = $:.find {|e| File.exist?(File.join(e, file)) }) && File.join(dir, file)
    end
Finds the full path to a gem's file relative it's load path directory.
 Returns nil if not found.