Removed all the duplicate methods that were getting the rate for each TimeEntry

and replaced them with a simple collector that uses the new TimeEntry#cost
method (that wraps the Rate API).

  #1924

app/models/hourly_deliverable.rb

@@ -10,13 +10,7 @@ class HourlyDeliverable < Deliverable
     # Get all timelogs assigned
     time_logs = self.issues.collect(&:time_entries).flatten
 
-    # Find each Member for their rate
-    time_logs.each do |time_log|
-      rate = Rate.amount_for(time_log.user, time_log.project, time_log.spent_on.to_s)
-      total += (rate * time_log.hours) unless rate.nil?
-    end
-    
-    return total
+    return time_logs.collect(&:cost).inject { |sum, n| sum + n} 
   end
   
   def profit # :nodoc: