clean up taxon collection structure

[mfrasca]

I think this would be practical and quick: if taxon collection would contain the fields:
epithet and rank, then, for all ranks at its own rank and above, the rank name associated to the containing taxon name.

to be concrete, Olea:
{rank:"genus", epithet:"Olea", authorship:"L.", family:'Oleaceae', tribus:'Oleeae'}
Phalaenopsis:
{rank:"genus", epithet:"Phalaenopsis", authorship:"Blume", family:"Orchidaceae", subfamily:"Epidendroideae"}
Inga:
{rank:"genus", epithet:"Inga", authorship:"Mill.", family:"Fabaceae", subfamily:"Mimosoideae", tribe:"Ingeae"}

[mfrasca]

I think we have been collecting most of this information in the ghini pocket taxonomy database, we should use that as a reference.