Added formatted otu category significance tables.

This includes a new option --alpha to determine what OTUs will be included in the output HTML tables.
Improvements to otu category significance tables.

Tables look better and provide links to each taxonomic level.
Removed premature break that I used for testing.
Merge branch 'master' into otu_cat_sig

Conflicts:
	personal_microbiome/format.py
Merge branch 'master' into otu_cat_sig

Conflicts:
	my_microbes/util.py
Fixed a few bad imports.
Merge pull request #29 from jrrideout/otu_cat_sig

Added otu_category_significance.py tables.