add Vips as CorePlugin, re #4258

public/assets/images/choice_checked.svg

public/assets/images/choice_unchecked.svg

public/assets/images/collapse.svg

public/assets/images/expand.svg

public/assets/images/icons/black/vips.svg

public/assets/images/icons/blue/assessment-mc.svg

public/assets/images/icons/blue/edit-line.svg

public/assets/images/icons/blue/vips.svg

public/assets/images/icons/red/vips.svg

public/assets/images/icons/white/vips.svg

...ic/assets/images/plus/screenshots/Vips/Vips_preview_1.png

...ic/assets/images/plus/screenshots/Vips/Vips_preview_2.png

...ic/assets/images/plus/screenshots/Vips/Vips_preview_3.png

resources/assets/javascripts/bootstrap/vips.js

resources/assets/javascripts/entry-base.js

resources/assets/javascripts/init.js

resources/assets/javascripts/lib/vips.js

resources/assets/stylesheets/scss/buttons.scss

resources/assets/stylesheets/scss/courseware/variables.scss

resources/assets/stylesheets/scss/forms.scss