henry `autosave`

[SimonEnsemble]

@ngantzler the Henry code runs till end but then fail to save results. get error: ERROR: LoadError: KeyError: key :sims not found. I think this is b/c u need to mkdir() the directory where results are stored. think this should be automatic. if it doesn't exist, make the directory. otherwise run risk of running tons of sims and then not writing the results.

[ngantzler]

In src/henry.jl there is a line here that checks if the output directory exists and creates it in the event that it doesn't. The directory should be rc[:paths][:simulations]. It looks like maybe the wrong key is being used. I've updated the docstring to reflect the current convention here.

[SimonEnsemble]

my henry calc did not run. it errored out b/c the key :sims is being called somewhere?