Start milestone 3

- Add functionality to query online sources (Keyservers, etc) for
  certificates.
- Use introducers to determine which UserIDs should be fetched from
  online soources. Check certifications before importing certifiactes
  into the local cert store.
- start docker image for local end-to-end testing.

docker/mta_provision/usr/bin/gen_tls_cert.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/bash
+
+DOMAIN=$1
+DIR=/etc/local_certs
+USER=hockeypuck
+
+if [ "$DOMAIN" == "" ] ; then
+  echo "USAGE: $0 DOMAIN"
+  exit 1
+fi
+
+if [ ! -d $DIR ] ; then
+  mkdir -p $DIR
+fi
+
+echo "create key material for $DOMAIN ..."
+openssl req -newkey rsa:2048 -keyout $DIR/$DOMAIN.key -nodes -x509 -days 365 -out $DIR/$DOMAIN.crt -subj "/C=DE/ST=HH/L=Earth/O=CompanyName/OU=IT/CN=$DOMAIN/emailAddress=email@example.com"
+chown $USER:$USER $DIR/$DOMAIN.key
+
+cp $DIR/$DOMAIN.crt /usr/share/ca-certificates/
+echo $DOMAIN.crt >> /etc/ca-certificates.conf
+
+# dont forget to run `update-ca-certificates` after all DOMAINs are done