experiment loop

[yuanqing-wang]

I've wrote a little experiment loop that pretty much ports from Pinot. https://github.com/choderalab/pinot/tree/master/pinot/app

@jchodera I love your 'loss function in dataset' idea and I've included in my datasets object. meanwhile I also feel like to have loss functions defined over graphs would just be a little bit more flexible:
https://github.com/choderalab/espaloma/blob/master/espaloma/metrics.py

let me know what do you think

[lgtm-com]

This pull request introduces 2 alerts when merging fcfb912 into 6ce8462 - view on LGTM.com

new alerts:

• 1 for Module imports itself
• 1 for Unused local variable

[maxentile]

Sounds good, will update from way "loss function in dataset" was attempted in #20