Tweak to make start.model.runs() wait for remote jobs.

When running on geo.bu.edu, the status message 'out' was coming back as character(0). Then nchar(out)>0 evaluates to logical(0) and causes an error. length(out)>0 evaluates to FALSE as desired.
Merge pull request #249 from ryankelly-uiuc/fix_start.model.runs

Tweak to make start.model.runs() wait for remote jobs.