NAWQAAN-206

* Minor cleanup before I add the new plot
* Mostly coming out of canvas research task
NAWQAAN-206

* Added Flow Duration plot to Hydrograph.js (tied to same data)
* Added Wrapper which constitutes both plots
* Cleaned up a bit of the code surrounding this connection
Merge pull request #197 from jiwalker-usgs/NAWQAAN-206

NAWQAAN-206