Add form fields to set the colours and the sections for the banner

Add migrations to store the information in the database

db/migrate/20180109081115_add_settings_to_banners.rb

@@ -0,0 +1,6 @@
+class AddSettingsToBanners < ActiveRecord::Migration
+  def change
+    add_column :banners, :background_color, :text
+    add_column :banners, :font_color, :text
+  end
+end

db/migrate/20180109101656_create_banner_sections.rb

@@ -0,0 +1,9 @@
+class CreateBannerSections < ActiveRecord::Migration
+  def change
+    create_table :banner_sections do |t|
+      t.integer :banner_id
+      t.integer :section
+      t.timestamps null: false
+    end
+  end
+end