check_drift changes

[mattmills49]

• [x] change default num_bins to null
• [x] include an option for other ggplot2 theme objects
• [x] change to percentage scales
• [ ] Fix scale name
• [ ] Look into changes for manipulating the variables

[mattmills49]

The way I fixed the scale name isn't the way to do it. If you add another scale object for colors then it gives a warning which is not what I want