Include storage class details in acorn volumes

[sangee2004]

Server version - acorn version v0.5.1-65-ge8a480d5+e8a480d5

Steps to reproduce the problem:
Deploy an app with volumes.
List the volumes using acorn volumes

Volume details does not include storage class information.

 % acorn volumes       
NAME                                       APP-NAME     BOUND-VOLUME   CAPACITY   STATUS     ACCESS-MODES   CREATED
pvc-e9b4d0fe-3b4e-4753-8fa1-79f37cfae99b   mytestnew1   pgdata1        10G        bound      RWO            13m ago

[sangee2004]

Tested with acorn version v0.5.1-72-gbd27105a+bd27105

We have VOLUME-CLASS attribute which displays the storage class of the volumes:

acorn volumes
NAME                                       APP-NAME   BOUND-VOLUME   CAPACITY   VOLUME-CLASS   STATUS     ACCESS-MODES   CREATED
pvc-6d5718fa-c525-41d9-8e32-ae78ff5cf6b3   mytest2    scratch-data   10G        local-path     released   RWO            11h ago