TESTING: summary plots and statistics from science testing

[jhamman]

Suggestions for further science testing plots and statistics:

• [ ] VIC vs. observations (scatter plots, e.g. example). For the SNOTEL dataset, peak swe, first snow free day, and swe duration. For the AMERIFLUX dataset, here we can plot mean turbulent fluxes, bowen ratios, etc.
• [ ] taylor diagrams
• [ ] add residuals to current plots, this will help us distinguish between lines that are close to each other.
• [ ] summary tables for each variable/metric

Suggestions for some minor improvements to existing

• [ ] fix y-limits on diurnal cycle plots so some of the variables with smaller magnitudes are legible
• [ ] don't make plots that don't have model data in them (e.g. fluxnet plot: 31.5907_-110.5092.png)
• [ ] add / change annual mean diurnal cycle plot to annual cycle (months on x axis).

xref #544