Start + Stop Script Using Wrong Shebang

The script files `start-develop.sh` and `stop-develop.sh` are using the following shebang: `#!/bin/sh`.
However, the scripts itself are not shell independent. This is because bash-specific substitutions are used.

Thus, we should explicitly state within the shebang that these scripts have to be ran with a bash (`#!/usr/bin/env bash`). Otherwise this will lead to problems down the line.