Add pull request template (#242)

.github/pull_request_template.md

@@ -0,0 +1,21 @@
+<!--- Title -->
+
+Description
+-----------
+<!--- Describe your changes in detail. -->
+
+Test Steps
+-----------
+<!-- Describe the steps to reproduce. -->
+
+Checklist:
+----------
+<!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
+<!--- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
+- [ ] I have tested my changes. No regression in existing tests.
+- [ ] I have modified and/or added unit-tests to cover the code changes in this Pull Request.
+
+Related Issue
+-----------
+<!-- If any, please provide issue ID. -->
+By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.