Adds preliminary github pull request template
Adds preliminary github pull request template

What:

* adds a pull request template

Why:

* standardizing the information in our pull requests will make
  reviewing code easier

Documenation: https://help.github.com/articles/creating-a-pull-request-template-for-your-repository/

MITLibraries/bento,MITLibraries/bento,MITLibraries/bento,MITLibraries/bento