Remove rustpkg

[brson]

My ml thread here: https://mail.mozilla.org/pipermail/rust-dev/2014-January/008224.html

It's a shame so many people spent so much energy both creating it and trying to use it but, but let's get it over with.

Remove rustpkg, its man page, its manual, and the packaging guide.

[salemtalha]

I'll give this a shot

[brson]

@salemtalha ok!

[jhasse]

Wow. So this is really already decided... I have to say I'm pissed.

[salemtalha]

@brson Question, when I remove the files mentioned in the issue the build process obviously fails, should I make a commit just with those removals and then fix the build process in a separate commit?