Remove uses of mechanize from webkitpy so that we don't need to autoinstall it.

This removes the status_server, botinfo, and omahaproxy modules which seemed to be
unused as well.

R=ojan@chromium.org
BUG=230706

Review URL: https://codereview.chromium.org/19693002

git-svn-id: svn://svn.chromium.org/blink/trunk@154466 bbb929c8-8fbe-4397-9dbb-9b2b20218538