It doesn't need to be that complicated, but may run into issues if they
have manually created folders or files named `dev`, rather than
automatically creating it as a link with `setup_for_hacking.sh`.
The exsting code was causing problems in Ubuntu anyway.
Proper exit codes are good practice.
Also, if a command fails somewhere in the middle of the script, it will
not proceed to the end of the script, outputting a message like "has
been restored to the installed configuration."
This step is purely aesthetical (for now), and easier on non-OSX
developers who may see the '*.app' in the path as a file extension,
rather than viewing the target as a directory.
If needed, this can be expanded to add more operating systems in the
future.
