Add Language model and LanguageController

spec/factories/definitions.rb

@@ -2,6 +2,7 @@ FactoryBot.define do
   factory :definition do
     pos { "n" }
     definition { "this is a definition" }
+    language_id { FactoryBot.create(:language).id }
     word_id { FactoryBot.create(:word).id }
   end
 end

spec/factories/languages.rb

@@ -0,0 +1,5 @@
+FactoryBot.define do
+  factory :language do
+    name { "MyString" }
+  end
+end

spec/factories/part_of_speech.rb

@@ -1,6 +1,7 @@
 FactoryBot.define do
   factory :part_of_speech do
     sequence(:pos) { |n| "test-#{n.to_s}" }
+    language_id { FactoryBot.create(:language).id }
     definition { "test definition" }
   end
 end