Adding hashtag model

db/migrate/20161104173623_create_tags.rb

@@ -0,0 +1,11 @@
+class CreateTags < ActiveRecord::Migration[5.0]
+  def change
+    create_table :tags do |t|
+      t.string :name, null: false, default: ''
+
+      t.timestamps
+    end
+
+    add_index :tags, :name, unique: true
+  end
+end