This allows to specify only
    tools/ConfigDb/update_ConfigDb.sh tools/ConfigDb/LOFAR_ConfigDb.json
instead of
    tools/ConfigDb/update_ConfigDb.sh /hosthome/workspace/git/LOFAR2.0/tango/tools/ConfigDb/LOFAR_ConfigDb.json

Also added the default ConbfigDb to serve as a clean start point.

The Python modules that the device depends on have to be
specified in the file requirements.txt in the same path
of the device.

Still not there because docker-compose appears to do some
things behind closed doors and I cannot figure them out yet.

This should allow to install 3rd party packages with pip.

There are more scripts coming.

Makes more sense that it is there.

This ensures that the file can be store in the host ${HOME} dir
outside of the container.

Also added ${TANGO_CONTAINER_ENV} that sets environment variables

The tools can dump/load/update the Tango ConfigDb.