Attribute filter policy conditional on existence of attribute?

[Rod Widdowson]

It turns out that right now if you do a ValueRegex PolicyRule and the attribute doesn't exist then the PolicyRule is false.  So 

	<PolicyRequirementRule xsi:type="ValueRegex" regex=".*" attributeID="attrfoo"/>

Right now (and only right now), you are testing for the attribute having any (String) value and thus being present.

However this behavior is not documented and may change in a future release.  In particular this area of code (how we deal with things not being there) is under active development so I'd defer strongly to Scott about this.  

Me, I'd not rely on this until I saw it documented.

	/Rod