Use the shared secret registration API directly (#7774)

* Use the shared secret registration API directly

rather than invoking the synapse module to do it. It's probably
a bit simpler, if anything, and allows for synapse to be run in
a separate container (or rather, avoids the javascript having to have
a copy of synapse source & server config).

* Make registration secret required

Update commander (8 major versions!) to get requiredOption

* Wrong options object :/

test/end-to-end-tests/synapse/getcfg.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+set -e
+
+if [ $# -eq 0 ]
+then
+    echo "Prints a configuration directive from the synapse installation"
+    echo "Usage: getcfg.sh <synapse config file directive>"
+    exit 1
+fi
+
+# activate the virtualenv so we have pyyaml
+BASE_DIR=$(cd $(dirname $0) && pwd)
+cd $BASE_DIR
+cd installations/consent/env/bin/
+source activate
+
+python -c "from yaml import load, Loader; import sys; print(load(sys.stdin, Loader=Loader)['$1'])" < homeserver.yaml