Add PR and issue templates

Also make a note about yapf formatting

.github/ISSUE_TEMPLATE.md

+Thank you for using Pika.
+
+GitHub issues are **strictly** used for actionable work and pull
+requests.
+
+Pika's maintainers do NOT use GitHub issues for questions, root cause
+analysis, conversations, code reviews, etc.
+
+Please direct all non-work issues to either the `pika-python` or
+`rabbitmq-users` mailing list:
+
+* https://groups.google.com/forum/#!forum/pika-python
+* https://groups.google.com/forum/#!forum/rabbitmq-users
+
+Thank you

.github/PULL_REQUEST_TEMPLATE.md

+## Proposed Changes
+
+Please describe the big picture of your changes here to communicate to
+the Pika team why we should accept this pull request. If it fixes a bug
+or resolves a feature request, be sure to link to that issue.
+
+A pull request that doesn't explain **why** the change was made has a
+much lower chance of being accepted.
+
+If English isn't your first language, don't worry about it and try to
+communicate the problem you are trying to solve to the best of your
+abilities.  As long as we can understand the intent, it's all good.
+
+## Types of Changes
+
+What types of changes does your code introduce to this project?
+_Put an `x` in the boxes that apply_
+
+- [ ] Bugfix (non-breaking change which fixes issue #NNNN)
+- [ ] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] Documentation (correction or otherwise)
+- [ ] Cosmetics (whitespace, appearance)
+
+## Checklist
+
+_Put an `x` in the boxes that apply. You can also fill these out after
+creating the PR. If you're unsure about any of them, don't hesitate to
+ask on the
+[`pika-python`](https://groups.google.com/forum/#!forum/pika-python)
+mailing list. We're here to help! This is simply a reminder of what we
+are going to look for before merging your code._
+
+- [ ] I have read the `CONTRIBUTING.md` document
+- [ ] All tests pass locally with my changes
+- [ ] I have added tests that prove my fix is effective or that my feature works
+- [ ] I have added necessary documentation (if appropriate)
+
+## Further Comments
+
+If this is a relatively large or complex change, kick off the discussion
+by explaining why you chose the solution you did and what alternatives
+you considered, etc.

CONTRIBUTING.md

@@ -63,4 +63,6 @@
 ## Code Formatting
 
 Please format your code using [yapf](http://pypi.python.org/pypi/yapf)
-with ``google`` style prior to issuing your pull request.
+with ``google`` style prior to issuing your pull request. *Note: only format those
+lines that you have changed in your pull request. If you format an entire file and
+change code outside of the scope of your PR, it will likely be rejected.*

README.rst

@@ -133,7 +133,9 @@
 *Pull requests that add or change code without coverage will most likely be rejected.*
 
 Additionally, please format your code using `yapf <http://pypi.python.org/pypi/yapf>`_
-with ``google`` style prior to issuing your pull request.
+with ``google`` style prior to issuing your pull request. *Note: only format those
+lines that you have changed in your pull request. If you format an entire file and
+change code outside of the scope of your PR, it will likely be rejected.*
 
 .. |Version| image:: https://img.shields.io/pypi/v/pika.svg?
    :target: http://badge.fury.io/py/pika