Removes category field in form for new payee.
Removes category from payees/show view
Adds database model data validations null: false and uniqueness.
Begins to add validations on User model.
Still testing.
Configs user of factory-girl-rails and shoulda-matchers.
Adds unit testing for user.
Changes heading. Arbitrary change.
Merge pull request #2 from climbapp/model-data-validations

Model data validations