Docker remove container before remove image (#928)

* add docker container removal

* remove container before deleting image

* update readme

* clean up and add assert not test

* test not docker command

* use shell.and_ correctly

thefuck/rules/docker_image_being_used_by_container.py

@@ -0,0 +1,20 @@
+from thefuck.utils import for_app
+from thefuck.shells import shell
+
+
+@for_app('docker')
+def match(command):
+    '''
+    Matches a command's output with docker's output
+    warning you that you need to remove a container before removing an image.
+    '''
+    return 'image is being used by running container' in command.output
+
+
+def get_new_command(command):
+    '''
+    Prepends docker container rm -f {container ID} to
+    the previous docker image rm {image ID} command
+    '''
+    container_id = command.output.strip().split(' ')
+    return shell.and_('docker container rm -f {}', '{}').format(container_id[-1], command.script)