Copy setup.py in addition to requirements file to allow Tox deployment in dev mode

Currently only `install-prereqs*.sh` `requirements*.txt` and `tox.ini` are copied from the current folder to the container when building the Tox environment. `setup.py` should also be copied, so that the `usedevelop` option in `tox.ini` can be set to true, avoiding duplication of dependencies in `setup.py` and `requirements.txt`.