Low: Stateful: Clean up implementation of Stateful (bnc#867372)

* Advertise the promote/demote actions in the RA metadata
* Use the standard OCF return code macros where appropriate
* Remove trailing whitespace
Merge pull request #393 from krig/stateful

Low: Stateful: Clean up implementation of Stateful (bnc#867372)
Medium: exportfs: Make unlock_on_stop_default=1 (bnc#864263)

The resource agent should really release all locks which the NFS server
holds when stopping the resource. When this option was introduced, the
default was kept as 0 for compatibility reasons with legacy kernels,
existing users and non-Linux systems.

This is a proposal to make 1 the default. In most cases, this is the
desired behavior, and not setting this option can lead to unexpected
failures.

Original changeset that introduced this parameter: 612559c9