(Global) Sensitivity Analysis Improvements

[lrennels]

Various improvements:

• update analyze function to use SimulationResults to access model results with keyword args instead of forcing user to pass an Array

• It would be best to be able to (as easily as possible) run analyze on data uncoupled from the need to run_sim or generate_trials. For example I added the keyword argument N to analyze in case it hasn't been sit in generate_trials. Think on other ways to keep this clean and simple.

• Streaming functionality, with or without file io, to handle large models like FUND (@rjplevin working on the first iteration of this).

• Implement Sobol Groups, and maybe Method of Morris (this would be done in GlobalSensitivityAnalysis.jl to enable groups for larger models such as FUND.

• Improved data visualization story (a focus for @lrennels this summer)