This function makes it easy to implement timestamping and no-clobber of files.
download_data(url, destdir = getwd(), timestamping = T, nc = F,
verbose = F, progress = F)The location of a file.
Where the file should be downloaded to.
Should only newer files be downloaded?
Should files of the same type not be clobbered?
Should cURL output be shown?
Should a progress bar be shown with cURL output?
A character string of the file path to the downloaded file.
If both timestamping and nc are TRUE, nc behavior trumps timestamping.