Change help system to only display the functions available to the user

Hi,
This is my very first github pull request :)

It should limit the functions displayed by -c help  to only those the user has permissions to use. The help text is now made up of the functions doc string with the section of the help it should be in as the first part of the docstring and the actual help text itself being hte second part, separated by a pipe character | 

I'd be be very interested in your comments, given my extremely rusty python skills, and limited understanding of how rhncli actually works

Enjoy saff

chris