fixes #5490 - ambiguous column in taxonomix pluck on Rails 3.2.8
(cherry picked from commit 3089c85f005425e8fec07c560ce5fb65ca25d45d)
fixes #4731 - Rails 3.2.8 causing _pkey constraint errors
fixes #812 - new permissions model, user group role and nest support, role filters for better granularity
fixes #3912 - add inheritance for locations / organizations
fixes #2739 - add ActiveSupport::Concern syntax to mixins
fixes #2411 - move files in /models to /concerns, /services, /mailers, /observers
