Switch to using CircleCI

[danielcompton]

Follows the pattern in clojure-emacs/clojure-mode#514. There was a large Travis test matrix, but it doesn't appear as if the MAKE_TEST env var was actually being used in the tests, they all seem to be running cask exec buttercup to do the testing.

You can see the tests running at https://circleci.com/gh/danielcompton/workflows/inf-clojure/tree/use-circle.

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Thanks!

[arichiardi]

Looks very good to me, let me try it out

[arichiardi]

Thank you it works like a charm