Moretablechange

This provides the changes @wasade requested 
- change biom.parse.parse_biom_format_json to biom.Table.from_json
- change biom.Table.get_biom_format_json_string to biom.Table.to_json
- remove biom.Table.get_biom_format_object
- remove biom.Table.get_biom_format_pretty_print

and revives the tests for parse_biom_format_json