Import OTT into OTU

[chinchliff]

Add the taxonomy to facilitate things like:

• annotating internal nodes with taxon names
• cross-referencing nodes from different trees on the basis of taxon assignment
• identifying percent taxonomic composition of trees and studies
• include more detailed taxonomic information in queries and reports

See also #13.

[chinchliff]

The basic OTT taxonomy import works. Now need to implement features.