Investigate adding a Plots type-recipe

[Omar-Elrefaei]

The user-recipe we have now works well enough for the majority of simple cases, but I think it will be much cleaner if Plots can handle AxisArrayTable type arguments generally not just our user-recipe specific signature f(m::AxisArrayTable...).

[Omar-Elrefaei]

use cases such as a fill plot(m.a, fill=(m.b, 0.2, :red)) currently does not work because Plots does not know how to extract the numbers from AxisArrayTable. (and right now we return an AxisArrayTable from m.b as opposed to a Vector like DataFrames does).