* Move system tests back into Action Pack
* Rename `ActionSystemTest` to `ActionDispatch::SystemTestCase`
* Remove private base module and only make file for public
`SystemTestCase` class, name private module `SystemTesting`
* Rename `ActionSystemTestCase` to `ApplicationSystemTestCase`
* Update corresponding documentation and guides
* Delete old `ActionSystemTest` files
Renames `Rails::SystemTestCase` to `ActionSystemTest` and moves it to a
gem under the Rails name.
We need to name the class `ActionSystemTestCase` because the gem expects
a module but tests themselves expect a class.
Adds MIT-LICENSE, CHANGELOG, and README for the future.
* Adds test case test
* Adds driver adapter test
* Adds tests for capybara seleium driver (testing the settings not
actually opening the browser to test capybara w/ selenium because that
would so so so slow)
* Adds tests for rack test driver
* Adds tests for generators
