add pacemaker cluster properties configuration

add pacemaker cluster properties configuration

Add support for ha_cluster_cluster_properties which is used
to set cluster-wide configuration.

See the README for details and examples.

do not fail if openssl is not installed

OpenSSL is used in the role and automated tests to generate random
preshared keys. Previously, OpenSSL was a dependency of pcs. That is no
longer the case since pcs-0.10.8-2.

In the role, keys are no longer generated on the controller, so the role
does not install OpenSSL there. Instead, preshared keys are now
generated on target nodes and the role newly ensures OpenSSL is installed on
target nodes.

In tests, OpenSSL is needed on the controller to test cases when
preshared keys are distributed from the controller. Tests ensure OpenSSL
is installed on the controller.