Added help for commands

[cldwalker]

Right now there isn't a consistent way to get help for any command. A few take '-h' and rip help only prints general help.

This branch enables help for commands using the assumption that ## means documentation as seen in a few places. Also fixes some doc inconsistencies.

While writing help tests I noticed that rip --version is using git which only works correctly when you're in the rip directory. Should I change it to print Rip::VERSION instead?

[josh]

Leaving this to defunkt, but I think the most the docs should be in the manpages.

Also, wouldn't want to use the double ## convention. Tomayko has a few conventions for this already in his rtomayko@shocco and rtomayko@rocco projects.

[cldwalker]

I reimplemented this as a plugin if that's more appealing. This time I didn't assume the '##' convention.