Enable automatic Gutenberg specific classes#105

When selecting a color in default Gutenberg color picker for text or background, the display is fine in the editor but doesn’t work on front-end. Gutenberg add class like has-cf-tertiary-color and .has-cf-secondary-background-color (which works with other classes as .has-background or .has-text-color) and the Core Framework didn’t write theses classes so the result is unstyled in front-end. With the Gutenberg coreframework addon, we would need and option in order for coreframework to automatically output theses derivatives classes.
For a button, neither the gutenberg picker nor the Coreframework metabox let us use a core framework color on a native gutenberg button. With the metabox selecting a class, the color is applied to the button wrapper and not to the background of the button, thus it is useless.