RSV: mine subtypes from NCBI GenBank

[atc3]

Some sequences that don't include G are assigned a genotype (A, B) by the submitter, and it's clearly marked under the "source" field of the "FEATURES" section in the GenBank entry. For example: JF905542

Not sure if we can pull this data from the NCBI Virus API but if we can, we should look for this data and substitute it in when our genotype alignments fail