Add "resizable" plugin option.
Add "width" and "height" plugin options.
Add overridable method for Map Layers plugin data.

This adds a new getter method for the Map Layers plugin layers.json data
to make the plugin more reusable.
Merge pull request #201 from kdeloach/topic/fix-infographic

Fix infographic distortion and add plugin options (resizable, width, and height)