introduce organizations

db/migrate/20170529215453_create_organizations.rb

@@ -0,0 +1,9 @@
+class CreateOrganizations < ActiveRecord::Migration
+  def change
+    create_table :organizations do |t|
+      t.string :name
+      t.text :description
+      t.string :picture
+    end
+  end
+end

db/migrate/20170531094817_add_organizaton_id_to_conference.rb

@@ -0,0 +1,5 @@
+class AddOrganizatonIdToConference < ActiveRecord::Migration
+  def change
+    add_column :conferences, :organization_id, :integer
+  end
+end