Additional simplifications in the JSON profile

Hi,

Following the decision to remove unnecessary nestings e.g. Obligations and Obligation as well as RequestDefaults and XPathVersion, I'd also like to put forward the following simplification.

Right now we have in the JSON Request an object called "Attributes" which is an array of Attributes.

Each Attributes object contains an array of Attribute objects. I find the naming rather confusing although it's directly in line w/ the XACML spec.

I would much rather rename Attributes to Categories and rename Attribute to Attributes.

Current state example:

{"attributes":[{"category":"urn:oasis:names:tc:xacml:3.0:attribute-category:resource","attribute":[{"attributeId":"username","value":"alice",}]}]}

Suggested change:

{"categories":[{"category":"urn:oasis:names:tc:xacml:3.0:attribute-category:resource","attributes":[{"attributeId":"username","value":"alice",}]}]}

Thoughts?

David.