Set up a development environment with docker (#387)

Signed-off-by: Konstantinos Sideris <sideris.konstantin@gmail.com>

docker/build.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+gb build
+
+# Generate the keys if they don't already exist.
+if [ ! -f server.key ] || [ ! -f server.crt ] || [ ! -f matrix_key.pem ]; then
+    echo "Generating keys ..."
+
+    rm -f server.key server.crt matrix_key.pem
+
+    test -f server.key || openssl req -x509 -newkey rsa:4096 \
+                        -keyout server.key \
+                        -out server.crt \
+                        -days 3650 -nodes \
+                        -subj /CN=localhost 
+
+    test -f matrix_key.pem || /build/bin/generate-keys -private-key matrix_key.pem
+fi