Add issue and pr templates

[MCGallaspy]

Adds a handy-dandy template for new PRs and issues. It's a new github feature! See the github docs: https://help.github.com/articles/creating-a-pull-request-template-for-your-repository/

I took the messages directly from out CONTRIBUTING.md file.

[benjaoming]

This is so freaking cool! I mean, Bugzilla had it since Jesus was born, but still: YAAAAAAAAAAA!!!!!!!11

[benjaoming]

Okay so self-assigning in order to open up a PR with a different format as @MCGallaspy suggested me to do... btw shouldn't this be targetted somehow for master? Then merge it from master->0.16.x->develop

[benjaoming]

Thinking it's okay to close this and continue discussing in the other PR for master.