Add Brakeman::RescanReport#to_s

lib/brakeman/rescanner.rb

@@ -244,4 +244,12 @@ class Brakeman::RescanReport
   def diff
     @diff ||= @new_results.diff(@old_results)
   end
+
+  def to_s
+    <<-OUTPUT
+Total warnings: #{all_warnings.length}
+Fixed warnings: #{fixed_warnings.length}
+New warnings: #{new_warnings.length}
+    OUTPUT
+  end
 end