Add MetadataMap input handler
Add TableConverter and ```biom convert```

Still needs unit tests
Improve error handling in TableConverter
Add unit tests for invalid input.
Add more unit tests for TableConverter.
Deprecate convert_biom.py

Fixes #168
Remove old_to_new_command

Moved this to pyqi.util. Fixes #176
Merge pull request #180 from jrrideout/death-march

Convert convert_biom.py to pyqi