numpy is a python requirement of the websockify package (it appears
there was some disucssion over *removing* this in [1], but did not
happen). Possibly these packages were installed a long time ago
before wheel support as it was taking a long time to build. But we
have wheels today, and later versions than the distro provides are
being dragged in anyway. Remove all distro installs.

[1] https://github.com/novnc/websockify/pull/163

Change-Id: I322dd9e1a07d8ce03c26cf3fcccebd6e21282fe4