purity/ploidy grid search

[jrafailov]

One more plot to be added!

this one will also go in the segment width distribution and will be called the Purity/ploidy grid search

data is provided for patient id 397089 and is called purple_sunrise.json

we are going to implement analogously to the plot attached within slack

we want the user to be able to interact with the plot. as such, users will "hover" over a particular square on the grid. Each square is represented as a single data point within the json above. Xmin/Xmax define the lower and upperbounds of the ploidy and ymin/ymax define lower and upperbounds of purity.

as always let me know if anything to clarify!

Originally posted by @jrafailov in #40