Quick Debug Develop with docker base images, locally reproduce CI docker testing

Assuming that CI fails on one or more docker builds and we know that our unit tests are sane but something is missing from the images. These commands can be followed to try to locally reproduce the docker CI testing:

In order to build the base images we can do (for gcc or icc):

docker build . --file docker/Dockerfile.cpu --tag test-base --build-arg arch=gcc

then we build devito image:

docker build . --file docker/Dockerfile.devito --tag test-devito --build-arg base=test-base

and then run tests:

# e.g. check notebooks
docker run --rm --name testrun test-devito py.test --nbval -k 'not dask' examples/seismic/tutorials/
# e.g. check tests
docker run --rm -e CODECOV_TOKEN=*** --name testrun devito_img pytest -k "not adjoint" -m "not parallel" --cov --cov-config=.coveragerc --cov-report=xml tests/