entrypoint: Build before starting

Because /v/share/jupyter/lab is now a volume, there is the potential
that it will be empty or out-of-date. We should always kick off a build
before starting jupyter-lab.

entrypoint.sh

@@ -13,4 +13,6 @@ cd $DATADIR
 [ ! -f $JUPYCNF ] && cp $JUPYDEF $JUPYCNF
 [ -f $JUREQFL ] && pip install -Ur $JUREQFL
 
+jupyter lab build
+
 ( $@ )