Add a param to prevent absolute value.

Author: link60

lib/time_difference.rb

@@ -78,12 +78,13 @@ def humanize
   end
 
   private
-  
-  def initialize(start_time, end_time)
+
+  def initialize(start_time, end_time, abs=true)
     start_time = time_in_seconds(start_time)
     end_time = time_in_seconds(end_time)
 
-    @time_diff = (end_time - start_time).abs
+    @time_diff = (end_time - start_time)
+    @time_diff = @time_diff.abs if abs
   end
 
   def time_in_seconds(time)