Splitting the summernote colorpicker into bg colorpicker and foreground
colorpicker seems to have been a bad idea as people tend to click on
the recent color button thinking it will open a dropdown.
This commit keeps the design that had been decided for colorpicker
template and do not change the "background-color" snippet option.
However, the colors for background and foreground text changes are
now displayed in an unique dropdown again, with reviewed style.
+ adapt the rte tour