ENH: method to compute a taxonomy based index
TST: tests for index computation
TST: added script usage test
ENH: allow for specifying an output column name
ENH: support for an arbitrary key
Addressing @ElDeveloper's comments
Addressing more of @ElDeveloper's comments
Fixed spacing
ENH: can dump to a mapping file, thanks @ElDeveloper
DOC: changelog mention
DOC: mapping file mention in output
DOC/ENH: typo and closing a file better now
Merge branch 'master' of github.com:qiime/qiime into dysbiosis_index

Conflicts:
	ChangeLog.md
BUG: zerodiv error when numerator is 0... weird
BUG: FloatingPointErrors managed now
STY: removing extra blank line
Merge pull request #1760 from wasade/dysbiosis_index

Dysbiosis index