Add mention of testing to 7##Refactoring small apps to use blueprints

[rpicard]

From @willkg

These sections are the home page, the user dashboard, the admin dashboard, the API and the company blog.

Before launching into steps, it's probably helpful to note that this is a refactoring and like any code refactoring, it's really handy to have decent tests so you can catch regressions caused by refactoring.