github: add issue and pull request templates

Fix: nodejs#5246

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,43 @@
+### Issue details
+
+_Please provide issue details here_.
+
+### Steps to reproduce/test case
+
+_Please provide necessary steps for reproduction of this issue, or better the
+reduced test case (without any external dependencies)_.
+
+### Affected node.js versions
+
+- [ ] v0.10
+- [ ] v0.12
+- [ ] v4.x
+- [ ] v5.x
+- [ ] master
+
+### Affected platforms
+
+- [ ] linux
+- [ ] windows
+- [ ] OS X
+- [ ] freebsd
+- [ ] solaris
+- [ ] other _(please specify which)_
+
+### Core part (if known)
+
+- [ ] buffer
+- [ ] child_process
+- [ ] cluster
+- [ ] crypto
+- [ ] dgram
+- [ ] dns
+- [ ] fs
+- [ ] http
+- [ ] https
+- [ ] net
+- [ ] tls
+- [ ] tty
+- [ ] vm
+- [ ] zlib
+- [ ] other _(please specify which)_

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,38 @@
+### Description of change
+
+_Please provide description of change here_.
+
+### Pull Request check-list
+
+_Please make sure to review and check all of these items_:
+
+- [ ] Does `make test` pass after this change?
+- [ ] Is commit message formatted according to [CONTRIBUTING.md][0]
+
+### Affected core part(s)
+
+- [ ] buffer
+- [ ] child_process
+- [ ] cluster
+- [ ] crypto
+- [ ] dgram
+- [ ] dns
+- [ ] fs
+- [ ] http
+- [ ] https
+- [ ] net
+- [ ] tls
+- [ ] tty
+- [ ] vm
+- [ ] zlib
+- [ ] other _(please specify which)_
+
+### SemVer
+
+What semver change does this change require?
+
+- [ ] patch _(no new APIs, no breaking changes)_
+- [ ] minor _(new APIs, no breaking changes)_
+- [ ] major _(breaking changes, or just too dangerous to be minor/patch)_
+
+[0]: https://github.com/nodejs/node/blob/master/CONTRIBUTING.md#step-3-commit