Add presence validations for required fields (#545)

* Adds basic validations for required fields

Also deletes a few extraneous .keep files

Does not add the family_id required field for user, since that breaks the basic test setup

* Restore keep files to this branch

* Remove Credit model and validate models behind ids

* Restore concerns .keep

app/models/transaction/category.rb

@@ -2,6 +2,8 @@ class Transaction::Category < ApplicationRecord
   has_many :transactions
   belongs_to :family
 
+  validates :name, :color, :family, presence: true
+
   before_update :clear_internal_category, if: :name_changed?
 
   DEFAULT_CATEGORIES = [