Remove outdated comment recommending knapsack

We are already using this.

.travis.yml

@@ -9,9 +9,6 @@ addons:
 
 # Set the timezone for phantomjs with TZ
 # Set the timezone for karma with TIMEZONE
-#
-# The test cases are roughly split according to their test times.
-# It would be better to use https://github.com/ArturT/knapsack.
 env:
   global:
     - TZ="Australia/Melbourne"