[Proposal] Add a help command

[Tim Penhey]

Hi All,

Right now there is no help command.  There is "--help" but it isn't
entirely intuitive.

  $ juju help
  error: unrecognized command: juju help

Hmm... --help works.

  $ juju --help add-relation
  - shows plain juju help, what you really want is:
  $ juju add-relation --help

Consider the commands given to an irc chanserv or nickserv responder.

  $ help -> list of commands
  $ help sub_command -> gives help on that command

This is exactly how bzr (and git) works:

  $ bzr help
  $ bzr help branch

I think it would be good to also support this.

Consider 'bzr help topics' and 'bzr help commands'.

'bzr help basic' gives the same result as 'bzr help' ( and bzr --help )

So... what I'd like to do is to add a "help" subcommand to juju, and
have it work more like bzr.

Perhaps also have the ability to add topics.  Topics are informational
and aren't commands, but may refer to commands.

For example, we could have something like:
  juju help glossary

Which may end up showing a lot of what is currently in the
doc/draft/glossary.txt file.

  `juju help topics` would list the topics that are available.


What do you think?

Tim