[bootstat] add OWNERS TEST=None BUG=chromium-os:22007 Change-Id: If4befce7fab22dbdeb50c5fccd8357380c91e85a Signed-off-by: Elly Jones <ellyjones@chromium.org> Reviewed-on: https://gerrit.chromium.org/gerrit/19756 Reviewed-by: Richard Barnette <jrbarnette@chromium.org>