ha-cluster: Remove resource agent's unnecessary config variables

This commit simplifies the OCF resource agent by removing unnecessary
variables leaving only three: master_cfg, master_ip and run_dir. The
test_mfsmaster_agent.sh script is also modified to reflect these
changes. Because the test which tests multiple instances provided by
this script no longer works (but this has been caused by one of
previous changes), it is commented out.

Change-Id: I377ba145a2682daffdff78be2b37017890460fc9