identity version resource and version fixes

Support for identity version and various version fixes:
* Added the notion of an unversioned service for a resource like the version
  resource.
* Changed all of the service filters so they could pass version through.
* Changed all the version resources to use unversioned services.

Change-Id: I92d6be9661560a8ced2648f1605fc3ffd8eeb91c
identity/v2 extension resource

Change-Id: I07741e6e74958c6d4e5097c0a25eebc3f8f0072b
Expand r_id to resource_id for more clarity

While working on documentation for the Resource class, I came back upon
the `r_id` name that exists on a bunch of methods. The name is an
argument to a bunch of public methods, so I think it should be as self
explanatory as possible.

Change-Id: I45c83c2f88f3cff6e3eb516c431183336a0b3201
keystore proxy methods and tests

Change-Id: Id0001d8ad24e1d8ab524ee5cdcaa6b90c7afa856
AttributeError trapped when it won't be raised

In this block, AttributeError will only be raised if the type name
doesn't exist on self. If that's the case, don't cover that up.
We could be hitting ValueError or TypeError here, but just let them
happen as they will.

Change-Id: I69b4d1aaaff6e04d061ef7891bc88f9924c9973d
Merge "keystore proxy methods and tests"
Merge "identity version resource and version fixes"
Merge "Expand r_id to resource_id for more clarity"
Merge "identity/v2 extension resource"