Update pointers to FTP --> ScienceBase

[trashbirdecology]

I am sure you're well aware, but datasets and sauer's results (many of them, not all) are archived at ScienceBase. This is briliant b/c SB has an API (and a companion package for streamlined retrieval, see package usgs-r/sbtools).

I am working on updating bbsAssistant -- it's currently functional enough to download and import the most recent dataset, need at least a few more working days to bring back up to speed.

Happy to see if there's anything our package can do to facilitate updating yours, vice versa, etc. etc.