GUACAMOLE-422: Remove "Canada/East-Saskatchewan" time zone, which was removed from the IANA database in release 2017c of the database.

From http://mm.icann.org/pipermail/tz-announce/2017-October/000047.html:

>
> Remove Canada/East-Saskatchewan from the 'backward' file, as it
> exceeded the 14-character limit and was an unused misnomer anyway.
>

guacamole/src/main/webapp/app/form/controllers/timeZoneFieldController.js

@@ -419,7 +419,6 @@ angular.module('form').controller('timeZoneFieldController', ['$scope', '$inject
         "Canada" : {
             "Atlantic"          : "Canada/Atlantic",
             "Central"           : "Canada/Central",
-            "East-Saskatchewan" : "Canada/East-Saskatchewan",
             "Eastern"           : "Canada/Eastern",
             "Mountain"          : "Canada/Mountain",
             "Newfoundland"      : "Canada/Newfoundland",