Property status attributes for deprecation

It should be possible to mark a resource property as deprecated, or possibly a number of other statuses including:
* deprecated
* experimental
* GA (generally available, the default)
* non-standard (for heat extension properties on AWS resources)

Along with the status, the following would also be useful:
* status_reason - description providing some context for the status, such as the what the alternative is for deprecated properties
* status_version - the heat release where the property moved into the status (eg 2013.2). For GA properties we could write a script which trawls git history and identifies what release each property was added in

This information will be consumed by:
* template guide resource type doc generation
* resource_type API