Adds image selector to the color wizard
Enables legends (intensity, color and custom) to use image backgrounds
Modifies color widget to allow the use of the same variable for color and image selection. Removes unsets
Merged with CDB-66. Fixed color widget so it works with the legends
Allows selecting an image in category legends
Fixes temp model
Points to the right branch in cdb.js
Fixes specs
CDB-233 #fixes Color/Category wizard image selector
Merge remote-tracking branch 'origin/feature/CDB-233' into release/2.4.0