API: Use HDF5 in filter_otus_from_otu_table
API: Use HDF5 in filter_samples_from_otu_table
API: Use biom_open in filter_taxa_from_otu_table
MAINT: Use load_table
Merge pull request #30 from ElDeveloper/filter-open-hdf5

Consolidates all the filter_otu* scripts