ktop: Install into /usr/sbin, not /usr/local/sbin

This preemptively fixes a Gentoo QA warning that will be introduced in
future versions of portage.

Signed-off-by: Richard Yao <richard.yao@clusterhq.com>
Merge pull request #832 from ryao/ktop

ktop: Install into /usr/sbin, not /usr/local/sbin