Test transform_image
Test transform_image

Exposes bug, e.g.:
```ruby
 FAIL ImageControllerTest#test_transform_rotate_left (1.32s)
        Expected response to be a redirect to <http://test.host/image/show_image/688136226> but was a redirect to <http://test.host/image/show_image/688136226?size=medium>.
        Expected "http://test.host/image/show_image/688136226" to be === "http://test.host/image/show_image/688136226?size=medium".
        test/controllers/image_controller_test.rb:1210:in `run_transform'
        test/controllers/image_controller_test.rb:1184:in `test_transform_rotate_left'
```

MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer,MushroomObserver/mushroom-observer