Add lint and test action

[cjmartian]

Overview

This pull request adds CI to lint and run tests.

(Please write a summary of your pull request here. This paragraph should go into detail about what is changing, the motivation behind this change, and the approach you took.)

Checklist

• Make sure that all of the tests pass, and fix any that don't. Just run bundle exec rake in your checkout directory, or review the CI job triggered whenever you push to a pull request.
• Make sure that there is 100% test coverage (the CI job will test for this). You can ignore untestable sections of code with # :nocov: comments. If you need help getting to 100% coverage please ask; however, don't just submit code with no tests.
• If you have added any new gem dependencies, make sure those gems are licensed under the MIT or Apache 2.0 license. We cannot add any dependencies on gems licensed under GPL.
• If you have added any new gem dependencies, make sure you've checked in a copy of the .gem file into the vendor/cache directory.

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