Add seed data for manual testing

Author: Charles Maresh

spec/dummy/db/seeds.rb

@@ -0,0 +1,10 @@
+
+if AdminUser.find_by(email: "admin@example.com").nil?
+  AdminUser.create!(email: "admin@example.com", password: "testing123", password_confirmation: "testing123")
+end
+
+categories = %w[Fruit Apple Pear Watermelon Vegetables Cucumber Squash Onion]
+
+categories.each do |name|
+  Category.find_or_create_by!(name: name)
+end