Client object creation is odd for at least dates

[Seanstoppable]

Creating a client model with dates looks like:

IrisHub::Models::PlannedShipment.new(:datetime => '2014-01-01')

Note that this is a string. A user can not just pass a valid date object as it throws an error

IrisHub::Models::PlannedShipment.new(:datetime => Time.now)
NoMethodError: private method `gsub!' called for Thu Jul 24 12:23:10 -0400 2014:Time

This seems wrong that a user needs to coerce a date into a string so it can be turned into a date so it can be serialized as a string.