Add app upgrade helper script

This script deploys a new app version, upgrades the given DAO to the
latest version of that app and builds the ABI files for the wrapper.

usage:

    scripts/upgrade.sh <app name> <dao address>

e.g.

    scripts/upgrade.sh token 0xfoobar

The DAO address can also be set as environment variable
$KREDITS_DAO_ADDRESS

scripts/upgrade.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+set -e
+
+rootDir=`pwd`
+
+app=$1
+daoAddress=$2
+if [ -z "$VAR" ]; then
+  daoAddress=$KREDITS_DAO_ADDRESS
+fi
+
+echo "## Deploying $app for $daoAddress"
+
+set -x
+cd "apps/$app"
+aragon apm publish major
+cd $rootDir
+aragon dao upgrade $daoAddress kredits-$app
+npm run build-json
+set +x
+
+echo "Done"