Ran images through ImageOptim.

This saves around 50KB of total file size with no observable degradation.
Merge pull request #2725 from refinery/optimise-images-with-imageoptim

Ran images through ImageOptim.
Merge pull request #1 from refinery/master

Update to refinery/master latest
Add shared example 'an image uploader'
Add 'uploader' tests to images_spec
Merge pull request #2726 from anitagraham/ImageSpecPart2

Shared example 'an image uploader'
Remove devise keys from locales
Remove authentication altogether.
Baby steps in removing authentication from refinery. (woohoo!)
Ensure that zilch is required wherever it is needed.
Don't rely on there being any menu items.
Mock things that we're not concerned with.

In these cases, we only care that the method in Refinery that is directly
responsible for allowing a controller returns false and that the active
plugins list is populated with the plugins that we expect to test our
assertions.