ExternalImage

edit

This is the Template ExternalImage It works along the lines of:

• http://stackoverflow.com/questions/19450262/mediawiki-set-external-image-width-by-value

You might want to add the following lines to MediaWiki:Common.css

.externalimage-holder {
    position: relative;
}
.externalimage-holder img {
    width: 100%;
    height: auto;
}

usage

{{ExternalImage|size=250px|title=Smiling Girl|link=http://philia-care.com/wp-content/uploads/2015/04/smiling_girl_small.jpg}}