GitLab

The syntax is similar to how TravisCI does it.

Travis test uses `get_macpython_enviroment` for CPython and
`get_python_enviroment` for PyPy.

Aliased PYTHON_VERSION to MB_PYTHON_VERSION.

Changed the test command to use get_python_enviroment instead of
get_macpython_enviroment.

Extended TravisCI matrix to cover PyPy.
The tests can now tell the implementation of PyPy apart from the CPython
version they emulate.

This changes how the the Python implementation is selected.  It's now
primarily based on enviroment variables.

Uses the PYPY_VERSION enviroment variable to determine the version of PyPy to
install.  An example has been added to the matrix in the readme.

Dashes were missing from untar on MacOS.

Redirect fill_pyver errors to stderr, instead of returning them as the
result.

See: http://bugs.python.org/issue29065#msg283984

From suggestion by Ralf G.

Always load library builders (for OSX as well as Manylinux).

Make configuration more general.

Move responsibility for source futzing back to the travis.yml file,
because we are now doing only one build per job.