Update Code of Conduct Attribution URLs

The Contributor Covenant URL has been updated as it was previously
redirecting to the Italian version of this document, and updates the
Ubuntu URL for currency and from insecure http://.

Author: davidjb

CODE_OF_CONDUCT.md

@@ -61,9 +61,9 @@ If you believe someone is violating the code of conduct, please report it by ema
 
 Sections of this Code of Conduct were inspired in by the following Codes from other open source projects and resources we admire:  
 
-- [The Contributor Covenant](http://contributor-covenant.org/version/1/4/)
+- [The Contributor Covenant](https://www.contributor-covenant.org/version/1/4/code-of-conduct/)
 - [Python](https://www.python.org/psf/codeofconduct/)
-- [Ubuntu](http://www.ubuntu.com/about/about-ubuntu/conduct)
+- [Ubuntu](https://ubuntu.com/community/code-of-conduct)
 - [Django](https://www.djangoproject.com/conduct/)
 
 *This Meteor Code of Conduct is licensed under the [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/) license. This Code was last updated on August 28, 2017.*