[c-nsp] Disabling "enable" command for users at privilege 0

[Kevin Graham]

> Is possible to disable "enable" command for users at privilege 0?

With a "parser view" you can exclude-command enable; then just assign
those users that view (ie. "username noc view LIMITED passsword 0 test").

This works under 12.4T, there is a (still undetermined) bug that prevents
it from working properly in earlier releases.