Refactor seed.rb (#2430)

db/seeds.rb

@@ -1,9 +1,7 @@
-web_app = Doorkeeper::Application.new(name: 'Web', superapp: true, redirect_uri: Doorkeeper.configuration.native_redirect_uri, scopes: 'read write follow')
-web_app.save!
+Doorkeeper::Application.create!(name: 'Web', superapp: true, redirect_uri: Doorkeeper.configuration.native_redirect_uri, scopes: 'read write follow')
 
 if Rails.env.development?
   domain = ENV['LOCAL_DOMAIN'] || Rails.configuration.x.local_domain
-  admin  = Account.where(username: 'admin').first_or_initialize(username: 'admin')
-  admin.save!
+  admin  = Account.where(username: 'admin').first_or_create!(username: 'admin')
   User.where(email: "admin@#{domain}").first_or_initialize(email: "admin@#{domain}", password: 'mastodonadmin', password_confirmation: 'mastodonadmin', confirmed_at: Time.now.utc, admin: true, account: admin).save!
 end