Add citations to EML

[RobLBaker]

EML should contain any/all citations used when generating the EML: for instance, if someone cites a protocol or SOP on DataStore, that should go into the Citations. If someone references a publication or text book used when generating the methodology, that should go in the Citations.

1. This is underway but was largely abandoned and could use substantial work
2. The function should take in a list (file?) of references in bibtex format
3. The function should insert the references into metadata
4. The references should be appropriately aligned with the xml formatting and not just dumped in to the citations. This will allow them to be pulled out and re-used later (for instance, to be sent up to DataCite, etc)

[RobLBaker]

sparse taxonomy support for taxa not in ITIS, GBIF, Worms?
Support for custom local taxa dabases?
taxadb, taxize integration?