Ensure the caching between order-select and order-sign is tied to the medication

[mojitoj]

There is a possibility, especially in cases where the order is initiated by someone other than the practitioner, that the medication order will change between the time of select-order and order-sign. This creates an issue where a response is returned from the cache at the time of order-sign which does not correspond to the medication in the order-sign request (and rather corresponds to the initial medication order at the time of order-sign).

Moreover, since an repeated order-select may be invoked if the clinician changes the medication order, we also need to ensure that the repeat order-selects are not returned from cache --unless the medication is identical.