Remove wait for .ember-application

Although this works sometimes, we should not be relying on the fact
that Ember can coalesce changes and render the entire DOM at once when 
the user first hits the page. Each test needs to consider the fact that 
the user interface is rendered asynchronously.
Fix flaky test

This test counted on a slow rendering in order to pass.
Use a more meaningful test code name
Don’t require a credit card for free items
Give disabled fields a style