Update for Intern 4

[jason0x43]

The tutorial documentation and code should be updated to focus on Intern 4.

[jason0x43]

Do we want the tutorial to require the user to setup a cloud testing service vs just using local Selenium?

[jason0x43]

Ah, we start with Selenium.

[jason0x43]

I went through the README and made some minor updates to the text, and pointed a bunch of links at the Intern 4 docs. I haven't walked all the way through the tutorial yet, but at least the completed version works properly for me.