Give xvfb some time to start up before starting the server in docker (#185)

run.sh

@@ -1,3 +1,8 @@
 #!/bin/bash
+start-stop-daemon --start --pidfile ~/xvfb.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :99 -screen 0 1024x768x24 -ac +extension GLX +render -noreset
+sleep 1
+
+export DISPLAY=:99.0
+
 cd /data
-xvfb-run -a -e /dev/stdout --server-args="-screen 0 1024x768x24" node /usr/src/app/ -p 80 "$@"
+node /usr/src/app/ -p 80 "$@"