[ci skip] Use https for jsbin

Update CONTRIBUTING jsbin to use polygit

Author: dfreedm

CONTRIBUTING.md

@@ -42,7 +42,7 @@ If you find an issue, please do file it on the repository. The [Polymer/polymer
 
 For issues with elements the team maintains, please file directly on the element's repository. If you're not sure if a bug stems from the element or the library, air toward filing it on the element and we'll move the issue if necessary.
 
-We love examples for addressing issues - issues with a Plunkr, jsFiddle, or jsBin will be much easier for us to work on quickly. You can start with [this jsbin](https://jsbin.com/cijadomupa/1/edit?html,output) which sets up the basics to demonstrate a Polymer element.
+We love examples for addressing issues - issues with a Plunkr, jsFiddle, or jsBin will be much easier for us to work on quickly. You can start with [this jsbin](https://jsbin.com/xukike/edit?html,output) which sets up the basics to demonstrate a Polymer element.
 
 Occasionally we'll close issues if they appear stale or are too vague - please don't take this personally! Please feel free to re-open issues we've closed if there's something we've missed and they still need to be addressed.
 

issue_template.md

@@ -2,7 +2,7 @@
 
 
 #### Live Demo
-http://jsbin.com/xukike/edit?html,output
+https://jsbin.com/xukike/edit?html,output
 
 #### Steps to Reproduce
 1. …