Contest language & top buttons

app/models/contest.rb

@@ -4,6 +4,7 @@
 #
 #  id                 :integer          not null, primary key
 #  allow_registration :boolean          default(FALSE)
+#  lang               :string           default("en")
 #  name               :string
 #  slug               :string
 #  team               :boolean          default(FALSE)
@@ -32,6 +33,7 @@ class Contest < ApplicationRecord
   friendly_id :name, use: :slugged
 
   validates :name, presence: true
+  validates :lang, inclusion: { in: Languages::AVAILABLE_LANGUAGES.map { |lang| lang[:id] } }
 
   generates_token_for :token
 end