added openvpn and started fixing dependency graph

modules/common/manifests/init.pp

@@ -3,7 +3,7 @@
 # Packages required by multiple modules
 #
 class common {
-  $pkgs=['build-essential','screen']
+  $pkgs=['build-essential','screen','octave','emacs','openvpn']
   
   package { $pkgs:
     ensure => present

modules/nilm/manifests/init.pp

@@ -10,6 +10,7 @@
 # Copyright 2017 John Donnal, unless otherwise noted.
 #
 class nilm {
+  require raspi
   $pip_url="http://puppet:wX27zvbA@pypi.wattsworth.net:8080/"
   $pip_cmd="pip3 install --upgrade --extra-index-url ${pip_url} --trusted-host pypi.wattsworth.net"