Few things

partial transition to biom 2.0, and su

* support for unique over a column hosts (ie, don't count multiple times for the same host_subject_id)
* use biom_open
* filterSamples -> filter
scratch that last comment about everything being BIOM 2.0 compat... heh. I'm actually going to revert, and leave this BIOM 1.3.1 for the time being as the code consuming this (the AG processing bits) are still reliant on 1.3.1