HYD-2812: updating url for moved fence-agents rpm.
HYD-2812: updating url for moved fence-agents rpm.

CentOS 6.4 has moved into the vault, and as such the url to the
fence-agents rpm has changed. This updates the cluster-sim Makefile
to refer to this adjusted url.

Change-Id: I36527d1588c4900e28f75d8b81868fd2605742b3

intel-hpdd/intel-manager-for-lustre,intel-hpdd/intel-manager-for-lustre,intel-hpdd/intel-manager-for-lustre