Added helper scrip to make tunnels from localhost to dev server

contrib/scripts/start-backend-tunnels.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+if [ $# -ne 1 ]; then
+    echo "Usage: $(basename $0) host" 1>&2
+    exit 1
+fi
+
+host=$1
+
+# change dir to root of git repository
+cd $(cd $(dirname $(readlink -f $0)) && git rev-parse --show-toplevel)
+
+# get all testnet ports from configs/
+testnet_ports=$(gawk 'match($0, /"rpcURL":\s+"(http|ws):\/\/[^:]+:([0-9]+)"/, a) {print a[2]}' configs/*_testnet*.json)
+
+for port in $testnet_ports
+do
+    ssh -nNT -L $port:localhost:$port blockbook-dev.corp &
+    pid=$!
+    echo "Started tunnel to ${host}:${port} (pid: ${pid})"
+done
+
+at_exit() {
+    pkill -P $$
+}
+
+trap at_exit EXIT
+sleep inf