[security-services] Proposed DoNotCache Condition

Title: Proposed DoNotCache Condition

I propose to add the following text after line 438 of the core spec.

----

<DoNotCacheCondition> [Optional]

Indicates that the assertion SHOULD be used immediately and MUST not be retained for future use. Note: no implementation is required to perform caching, however any that do so MUST observe this Condition.

----

The coresponding changes to the schema would be to derive <DoNotCacheCondition> from <Condition>. I don't know if we need to derive an abstract type from <ConditionAbstractType> of just derive <DoNotCacheCondition> directly. It is hard to imagine any further extension to <DoNotCacheCondition>.

Suggestions? Opinions?

Hal