Datastore on Show Instance Should Not Be a Dict

From:

+-----------+-----------------------------------------------+
|  Property |                     Value                     |
+-----------+-----------------------------------------------+
|  created  |              2014-01-12T22:17:16              |
| datastore | {u'version': u'mysql-5.5', u'type': u'mysql'} |

To:

$ trove show 160e571f-afae-4ac8-aec0-7b2e55846e07
+-------------------+--------------------------------------+
|      Property     |                Value                 |
+-------------------+--------------------------------------+
|      created      |         2014-01-12T22:17:16          |
|     datastore     |                mysql                 |
| datastore_version |              mysql-5.5               |

Change-Id: I1542869760ab0010a2ada4ed16a0b526dc233220
Closes-Bug: #1254141
Merge "Datastore on Show Instance Should Not Be a Dict"