Add template for new issues & pull requests

[codewithtyler]

Last week, GitHub announced a new feature that allows project maintainers to add information about the project as placeholder text on issues and pull requests.

Seeing as we keep getting pull requests that don't include updated release notes I think we should create a template for our pull requests that include some basic information on what needs to be included in each pull request.

The same could be done for issues as well. If we decide to add one for issues I think it should incude some information that points to the wiki.

[sayedihashimi]

+1

[codewithtyler]

Any suggestions what we should include on the pull request template? We don't have a Contributing.md file so I'm not sure what all to include.

cc: @sayedihashimi @kentcooper