Implement BrowserType.connect_over_cdp - chromium only

[trgoodwin]

This PR is heavily influenced by #37 by @oliverswitzer. Thank you for the inspiration and launching off point.

I'm proposing a slightly different contract that is consistent with the current approach used with BrowserType.launch

• Implements Browser.browser_type/1

• Implements BrowserType.connect_over_cdp/3

• Adds httpoison as test dependency in order to fetch WS url from chrome debugger tools endpoint

• Refactors how launch options are provided to BrowserType.launch so they can be passed down and not require trying to override using Application.put_env for tests. I believe that is the likely culprit causing the timeout issues in the previous pull request as once thats passed in args: ["--remote-debugging-port=#{@remote_debug_port}"], everything else breaks.