Fix tests

[SBeator]

It seems that the tests are failed so I send this pull request to fix all the tests:

1. Sanity test: The reference image is missing in repository, so add the two images in.
2. Unit test: The usage information have been updated so update the expect usage.
3. Smoke test: There is an animation which takes 800ms when the test page is loaded, we need to add 1000ms delay before we can take the screenshot.

What's more, it seems the test are all failed for all the other pull request but the check always says pass:
e.g:
The check for #726 is passed.
But actually if you click the travis report url: https://travis-ci.org/garris/BackstopJS/builds/364986140?utm_source=github_status&utm_medium=notification, you can see that the unit test is failed.

I don't have permission to access the docker cloud check, not sure what checks will it do, but I assume there are also some failure tests in the docker cloud check if it runs smoke tests.