Enforce cluster roles

[bronhaim]

Defining cluster policies is part of fence-cluster-config policies attribute - this attribute is list of policies we want to enforce. Policy == condition which in-case the condition passes we want to disable to controller main loop until the condition stops to be valid.
We can make it generic using fence-cluster-policy-configs or hard-code few rules that user can enable or not. such as fence-limit, which disables the fence logic if more than x percentages of nodes are monitored as not-ready to avoid overloading in cluster.