Create template for pull requests and commits

[mnlevy1981]

A template for pull requests would let us provide developers with a check-list to make sure the code has been properly tested. Things to include in check list:

• Is code bit-for-bit with previous tag?
• Does pull request address an issue ticket? If so, which one?
• Has the MARBL API changed?
• What testing has been done?
• Make sure code meets with standards outlined in design document / wiki

[mnlevy1981]

@klindsay28 pointed out that CTSM is having a good discussion about how github lets you provide multiple templates for different types of issues:

ESCOMP/CTSM#422

@billsacks went as far as to set up a toy repository with multiple templates... the templates are in

https://github.com/billsacks/ctsm-github-multiple-issue-templates/tree/master/.github/ISSUE_TEMPLATE

and when you click on "New Issue" you get taken to

https://github.com/billsacks/ctsm-github-multiple-issue-templates/issues/new/choose