Issue #26 - Adding taggable feature
Issue #26 - Updates to tagging using new mongoid_taggable GEM
Issue #26 - Updated factories to match tag assignment format.
Merge pull request #33 from alim/Issue_26

Issue 26 - Adding tag attributes for ImmuneResponse and Macrophage classes.
Merge pull request #34 from alim/development

Development - Merge latest development branch for Issue #26