Use _load/_dump to serialize when present

lib/ice_cube/time_util.rb

@@ -23,14 +23,21 @@ def self.serialize_time(time)
       if defined?(:ActiveSupport) && const_defined?(:ActiveSupport) && time.is_a?(ActiveSupport::TimeWithZone)
         { :time => time, :zone => time.time_zone.name }
       elsif time.is_a?(Time)
-        time
+        if time.respond_to?(:_dump)
+          time._dump
+        else
+          time
+        end
       end
     end
 
     # Deserialize a time serialized with serialize_time
     def self.deserialize_time(time_or_hash)
-      return time_or_hash if time_or_hash.is_a?(Time) # for backward-compat
-      if time_or_hash.is_a?(Hash)
+      if time_or_hash.is_a?(Time)
+        time_or_hash
+      elsif time_or_hash.is_a?(String)
+         Time._load(time_or_hash)
+      elsif time_or_hash.is_a?(Hash)
         time_or_hash[:time].in_time_zone(time_or_hash[:zone])
       end
     end