Auto merge of #4289 - johnthagen:usage-fix, r=alexcrichton
authorbors <bors@rust-lang.org>
Mon, 17 Jul 2017 22:52:23 +0000 (22:52 +0000)
committerbors <bors@rust-lang.org>
Mon, 17 Jul 2017 22:52:23 +0000 (22:52 +0000)
Add "uninstall" command to cargo --help

Closes #4285


Trivial merge