Fixes host stats for VMWareVCDriver

Host stats for VCDriver should collect aggregate cluster stats
rather than that of a single host in the cluster.

Fixes: bug #1190515
Change-Id: I37e46995c5da2e3052e8178098afee7c8061bb3c
(cherry picked from commit 92983257bb8e19dff54cc8a2188cc692dcafe5b8)
Merge "Fixes host stats for VMWareVCDriver" into stable/grizzly