generic download script.  downloads file to specified directory, compares file with current file.  if new, then updates the current directory.  this is what most of our downloaders do.
generic download script.  downloads file to specified directory, compares file with current file.  if new, then updates the current directory.  this is what most of our downloaders do.


Former-commit-id: 95ca5f6f7974a05182bc15f94ba74b8a4ca0cb69
julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine,julie-sullivan/phytomine