Add validation / authz information to command help

This extends the help rendering system by adding the schema data, created from
our validation input, to the output.  Actually rendering the schema down into
markdown is delegated to the schema object itself, since that avoids smearing
knowledge about how the code is implemented through the help subsystem.

This only adds the core infrastructure, and adds support for generating the
access control documentation to the code.  No customization of what is output
is yet available, since no need for it was immediately identified.

https://tickets.puppetlabs.com/browse/RAZOR-196
Signed-off-by: Daniel Pittman <daniel@rimspace.net>