removed 3 columns from organization model / table

part of PT story https://www.pivotaltracker.com/story/show/79157840
- created migration to remove the fields
- cleaned model to represent new state
- made rspec tests match new requirements
- amended the organization factory
- changed features to represent new model
- changed fields shown in active admin views
fixed errors in db schema file
remove unneeded params line from spec model
Merge pull request #52 from PurityControl/org_refactor

removed 3 columns from organization model / table