Fix some failing round trips

In some Debian environment two of the round trips in to_yaml_spec.rb were failing (those using `.month_of_year` and `day_of_year`. Applying the same fix as the one used in 4bf1718 to fix ice-cube-ruby#483 solved the issue.

This patch proposes that corresponding change to `/spec/examples/to_yaml_spec.rb`.

spec/examples/to_yaml_spec.rb

@@ -78,7 +78,7 @@ module IceCube
     end
 
     it "should be able to make a round-trip to YAML with .day_of_year" do
-      schedule1 = Schedule.new(Time.now)
+      schedule1 = Schedule.new(Time.zone.now)
       schedule1.add_recurrence_rule Rule.yearly.day_of_year(100, 200)
 
       yaml_string = schedule1.to_yaml
@@ -112,7 +112,7 @@ module IceCube
     end
 
     it "should be able to make a round-trip to YAML with .month_of_year" do
-      schedule = Schedule.new(Time.now)
+      schedule = Schedule.new(Time.zone.now)
       schedule.add_recurrence_rule Rule.yearly.month_of_year(:april, :may)
 
       yaml_string = schedule.to_yaml