Export survey timestamps

[isaactpetersen]

I'm not sure if this is already a feature and I'm just missing how to implement it, but I'm not seeing an option to export the survey timestamps--e.g., see the "survey" argument of the exportRecords() function from the redcapAPI package. Love the package guys!

[wibeasley]

Thanks for the input, @dadrivr. I'll close this issue, because it's a duplicate of #159. It certainly sounds like there are enough people to make this worth implementing. I'll try to do it in the next week or two.