Make Image module active config save format match the default yml file.

This is a sub-issue of #1938580: [META] Make active config save format match the default yml file (order and quotes). Check meta issue for Steps to reproduce and Coding standards

Files need to be fixed
image.style.large.yml
image.style.medium.yml
image.style.thumbnail.yml

Files fixed already
image.settings.yml

Remaining tasks

• Create patch. Contributor Task doc: http://drupal.org/node/1424598