Fix the failing tests.

* Focus can only be checked for if the window is currently in focus.
* .error is used by mocha to indicate errors. Namespace all checks for .error to the view.
* Up time timeout for mocha to 5seconds and the intern to 120seconds.
* Add a unit test for signing in with a non-existent user (see https://github.com/mozilla/fxa-js-client/issues/74)

fixes #489