Start IntegrationTestCase.

Not much here, but getting something down is a start.
Start to flesh out IntegrationTestCase.

Start adding an integration test for IntegrationTestCase - how meta.
Remove dead code.

This code is no longer needed, it can be removed safely.
Very crude dispatch cycle is working now.

The code is pretty simple right now as it doesn't attempt any fancy
footwork around mocks or giving you ways to only get the just the view
without the layout. It is also not possible to get the view variables
just yet.

I've also added a stub response to smooth over any issues where someone
might try and send a response by accident or on purpose :)
Fix header manipulation.

Convert headers from the format humans expect to the format PHP uses
internally.
Implement assertResponseXX methods.

Add positive tests for assertResponseXX methods, the negative tests seem
less useful right now.
Add assertRedirect()
Fix typos and expand docs.
Add assertResponseContains() to IntegrationTestCase.
Add more assertion methods.
Add exception handling to IntegrationTestCase.

Rendering exceptions is part of the 'integration' aspect of integration
testing.
Fix typos.
Merge pull request #4467 from markstory/integration-testcase

Start Integration testcase