Add user model with devise; Add sign-in link to navbar
Add admin boolean flag to user
Add better errors; Update navbar with link to sign in and out; New user session forms
Rake task for creating default admin user
Update db/schema.rb
Update user sign-in
Merge branch 'issues/3/usermodel' of https://github.com/ocsoftware/chs_inventory into issues/3/usermodel
Merge pull request #3 from ocsoftware/issues/3/usermodel

Create user model and incorporate Devise
Rename ItemInStock#in_stock to #quantity

Also add back in the migration for the items_in_stock table, got left
out somehow
Enforce authorization