Add templates for issues and pull requests (cucumber#979)

* Add template for isses

This adds a template for issues:
https://github.com/blog/2111-issue-and-pull-request-templates. It's
based on the template from this site
https://github.com/TalAter/open-source-templates.

* Add template for pull requests

This adds a template for pull requests:
https://github.com/blog/2111-issue-and-pull-request-templates. It's
based on the template from this site
https://github.com/TalAter/open-source-templates.

* Tweaks to copy in issue template

* Tweaks to copy in pull request template

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,48 @@
+<!-- These sections are meant as guidance for you, to help you give the kind of information we'll need to help with your issue. If a section  doesn't seem to fit, just skip it.
+
+In general: Please provide as much information as you can to help us solving your problem -->
+
+## Summary
+
+<!--- Provide a general summary description of the issue -->
+
+## Expected Behavior
+
+<!--- If you're describing a bug, tell us what should happen -->
+<!--- If you're suggesting a change/improvement, tell us how it should work -->
+<!--- Feel free to use Given / Then / Then if that helps, but please add some plain-language context too -->
+
+## Current Behavior
+
+<!--- If describing a bug, tell us what happens instead of the expected behavior -->
+<!--- If suggesting a change/improvement, explain the difference from current behavior -->
+
+<!--- If you have got some output place it in the code block below. Otherwise remove it. -->
+~~~
+~~~
+
+## Possible Solution
+
+<!--- Not obligatory, but suggest a fix/reason for the bug, -->
+<!--- or ideas how to implement the addition or change -->
+
+## Steps to Reproduce (for bugs)
+
+<!--- Provide a link to a live example, or an unambiguous set of steps to -->
+<!--- reproduce this bug. Include code to reproduce, if relevant -->
+1.
+2.
+3.
+4.
+
+## Context & Motivation
+
+<!--- How has this issue affected you? What are you trying to accomplish? -->
+<!--- Providing context helps us come up with a solution that is most useful in the real world -->
+
+## Your Environment
+
+<!--- If you're reporting a bug, include as many relevant details about the environment you experienced the bug in -->
+* Version used:
+* Operating System and version:
+* Link to your project:

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,39 @@
+<!-- These sections are meant as guidance for you. If something doesn't fit, you can just skip it. -->
+
+## Summary
+
+<!--- Provide a general summary description of your changes -->
+
+## Details
+
+<!--- Describe your changes in detail -->
+
+## Motivation and Context
+
+<!--- Why is this change required? What problem does it solve? -->
+<!--- If it fixes an open issue, please link to the issue here. -->
+
+## How Has This Been Tested?
+
+<!--- Please add tests for changes to the code, otherwise we probably won't merge it -->
+
+<!--- Please describe in detail how you tested your changes. -->
+<!--- Include details of your testing environment, tests ran to see how -->
+<!--- your change affects other areas of the code, etc. -->
+
+## Screenshots (if appropriate):
+
+## Types of changes
+
+<!--- What types of changes does your code introduce? Put an `x` in all the boxes that apply: -->
+- [ ] Bug fix (non-breaking change which fixes an issue)
+- [ ] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+
+## 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've added tests for my code
+- [ ] My change requires a change to the documentation.
+- [ ] I have updated the documentation accordingly.