Map websocket/tests/hybi directory to root on pywebsocket

Just map it to root so that we don't need to write "websocket/tests/hybi"
in all tests.

BUG=none

Review URL: https://codereview.chromium.org/96493002

git-svn-id: svn://svn.chromium.org/blink/trunk@162966 bbb929c8-8fbe-4397-9dbb-9b2b20218538