Issue with plotting nan values.

[nkorinek]

When plotting nan values, occasionally the plots will be broken because of how we stretch values. Need a fix to make sure earthpy.plot.plot_rgb() can account for nan values and gracefully plot the data regardless.

[nkorinek]

this is what the images look like when nan values are not accounted for.

This is how the plot is supposed to look. I got the second plot by masking the nan values out with numpy masking.