medium: ui_node: Fix handling of default arguments (bnc#889673)

Syncronize the code for some node commands with the documentation,
and allow the node name to be omitted where it makes sense.
medium: crm_pssh: Degrade functionality if pssh is unpatched

Try to detect if the version of pssh available has been patched,
and avoid using patch features if that is not the case.
medium: ui_node: Require node arg. for node fence|clearstate
Merge pull request #51 from krig/pssh-version

medium: crm_pssh: Degrade functionality if pssh is unpatched
Merge pull request #50 from krig/node-clearstate

medium: ui_node: Fix handling of default arguments (bnc#889673)