added module docstring
more doc bits
iter_ is tracked during execution
more docs
sphinx is pain:
doc additions
sphinx and doctest are insane.
merging
Merge branch 'master' of github.com:biocore/scikit-bio into workflowdoc

Conflicts:
	skbio/core/workflow.py
lets see what travis does
more travis issues
i think it works now?
removing NotExecuted abuse
DOC: addressing module comments, thanks @ElBrogrammer
MAINT: removing unused variable, thanks @ElDeveloper
DOC: cleaned up method, thanks @ElBrogrammer
DOC: formal type added to a parameter, thanks @ElBrogrammer
DOC: left out some =
DOC: resovling minor issues
DOC: indent