add issue and PR templates for github, adapted from react project tem…

…plates

.github/ISSUE_TEMPLATE.md

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+**Do you want to request a *feature* or report a *bug*?**
+
+**What is the current behavior?**
+
+**If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. Your bug will get fixed much faster if we can run your code and it doesn't have dependencies other than Air Traffic Control. Paste the link to your JSFiddle (https://jsfiddle.net/Luktwrdm/) or CodeSandbox (https://codesandbox.io/s/new) example below:**
+
+**What is the expected behavior?**
+
+**Which versions of Air Traffic Control, and which browser / OS are affected by this issue? Did this work in previous versions of Air Traffic Control?**

.github/PULL_REQUEST_TEMPLATE.md

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+**Before submitting a pull request,** please make sure the following is done:
+
+1. Fork [the repository](https://github.com/airplane-mode/air-traffic-control) and create your branch from `master`.
+2. Run `npm install` in the repository root.
+3. If you've fixed a bug or added code that should be tested, add tests!
+4. Ensure the test suite passes (`npm run test`).
+5. Make sure your code lints (`npm run lint`).
+
+**Learn more about contributing:** https://airplane-mode.github.io/air-traffic-control/docs/contributing.html