[defect] OCF needs exact lexical rules

[jnpkrn]

Currently, pacemaker seems to naively rely on some characters
never used in the name of the paramater to be passed to resource
agent, and would probably go south if that was the case.
However, OCF currently offers no such lexical assumptions.
We need to establish formal (hence predictable) grounds
in the specification in general, this one being low-hanging fruit
with significant impact, but the subtask would be to review
which other places are likewise not covered.

[jnpkrn]

As demonstrated in
#15 (comment)
na(t)ive shell approach to environment variables also makes using
some characters in the parameter names basically frowned upon.

We have a benefit of considering these practical use cases now to restrict
lexical rules sensibly.