MAINT: no more table factory, and added Table._to_sparse
STY
Merge branch 'master' of github.com:biocore/biom-format into no_to_sparse

Conflicts:
	biom/commands/table_converter.py
	biom/parse.py
	tests/test_table.py
fixing table_factory issues
BUG: to_json calls
DOC: table_factory -> table
Merge pull request #358 from wasade/no_to_sparse

MAINT: no more table factory, and added Table._to_sparse