Update pp plots

Put confidence bands on the pp plots. This is pretty untested though-- sorry!

changed milestone to %0.4.2

assigned to @gregory.ashton

mentioned in issue #323 (closed)

mentioned in issue #324 (closed)

changed milestone to %0.4.4

Bumping this to 0.4.4 as I haven't had time to do it quite yet but will do soon.

changed milestone to %0.5.0

mentioned in merge request !433 (merged)

closed