chore(ckeditor): Convert blockimagepaste plugin to AMD

@jdalsem This is what I meant. Is this what you tried? Any reason not to go this way?
Tested and AMD loading works fine, however it is not usable in the current way. In the ckeditor config it is determined if this extra JS should be loaded (so someone should be able to turn it off). However with the way you are loading the AMD module now, it always gets loaded (instead of on demand). You can test it by removing the extraPlugins setting in the config.