Selenium Tests

This pull request gives a script for programmatically navigating privly-applications in several contexts:

* Chrome without an extension.
* Chrome with an extension.
* Firefox without an extension.
* Firefox with an extension.
* All the above on [SauceLabs](https://saucelabs.com/)

The only thing that doesn't currently work is running these tests on SauceLabs for the Chrome extension context, but I am working with the people at SauceLabs to figure out the issue.

Following merging this I will merge similar requests on privly-web, privly-firefox, and privly-chrome that will run these tests on TravisCI every time commits are pushed to a remote that is properly plugged into TravisCI and SauceLabs.