Add CircleCI support (#91)

* Initial guess at supporting CircleCI

joerick/cibuildwheel#90

* Add note about setup_remote_docker on Circle

* Add diagnostic print of entire docker command

* Add more diagnostic prints

* Retrigger for Circle build

* Preliminary .circleci/config.yml

* Add workflows to Circle

* drop osx on circle

* call python3 directly on circle

* drop repeat pip install

* use a virtualenv on circle

* use a virtualenv on circle... again

* use a virtualenv on circle... again... again

* setup_remote_docker on circle

* try to manually copy into docker on circle

* correct Host

* correct docker calls

* refactor docker calls

* take 2 on the docker cp destination

* more docker cp debugging

* more docker cp debugging... again

* docker cp explicitly to /project

* wait until docker container is up

* wait until docker container is up... again

* and copy results back

* and copy results back... again

* create /output in container

* create /output in container... again

* copy contents of container's /output

* Retrigger ci

* fix merge typo

* fix monotonic

* always install monotonic

* always install monotonic... again

* correct to use project_dir

* wait a bit longer and a bit smarter

* wait a bit longer and a bit smarter... again

* add back circle osx

* add back circle osx... again

* py2/3 for circle

* py2/3 for circle... again

* use python2.7 image on circle linux

* (mostly) remove unused ci host identification code

* skip inspecting docker for the container, just retry copy on failure

* cleanup docker container and images

* fully remove ci host detection

* docs and tidy

* add circle badge

.circleci/prepare.sh

@@ -0,0 +1,7 @@
+$PYTHON --version
+$PYTHON -m pip --version
+$PYTHON -m pip install -q --user --ignore-installed --upgrade virtualenv
+$PYTHON -m virtualenv -p $PYTHON venv
+venv/bin/python -m pip install -r requirements-dev.txt
+venv/bin/python -m pip freeze
+venv/bin/python --version