Add metadata support for volume

Now able to pass metadata to the create method,
as well as update it with set, and remove it with unset.
I'm currently passing it as an optional param like the following:
--meta-data=key1=value1
which seems weird, what about
--meta-data=key1:value1
I'd have to update type too if that is the case.

Change-Id: I0fc8398768da015c1f53c5c564c68a2cfb53e778
Add policy to identity v3

use file for data blobs
add create/set/delete/show/list policy for v3

Change-Id: I5f68ef89dfb2241ea1aca00736ee6df5f6f03a9b
Merge "Add policy to identity v3"
Merge "Add metadata support for volume"