Fix #487
Merge branch 'master' of github.com:biocore/biom-format into fix_487
Merge branch 'master' of github.com:biocore/biom-format into fix_487
fixing commands
Collapse now only stores a list of collapsed ids
Modify to_hdf5 so it correctly formats collapsed_ids
Merge pull request #501 from antgonza/fix_487

Fix #487
Merge pull request #507 from josenavas/issue503

Collapse stores a list of original ids
Raising a useful error and adding a speccific tests
It turns out that None is allowed in taxonomy...
Adding a specific test for to_hdf5 allowing taxonomy=None
Adding comments to complex list comprehension
Breaking up list comprehensions
Merge pull request #508 from josenavas/issue506

Raising a useful error and adding a speccific tests