Fix query strings for GenBank datasets to include the hostname
(ftp.ncbi.nih.gov).  Also, they use the "curl" driver, not the "ftp"
driver.
No need for driver state in the AG curl driver.
Add syndicate.ag, syndicate.ag.curation, syndicate.ag.datasets packages.
This factors out reusable functionality from curate-ftp.py, so other
curation tools can use it.  Also, add a stub for curating local disk.
Built the AG drivers along with the AG, and install them along with the
AG.
Remove useless code