Initial draft of plugin to resize/center images in a modal

This is an initial draft to publish a plugin to resize stuff in the modal.
Currently we still need:

* [ ] check if we really want to include third party stuff like polyfills
* [ ] implement an option to use the resize/center on a specific modal
* [ ] test cross devices and browser
* [ ] test edge cases
* [ ] add a specific test-case
* [ ] document the plugin