Add spring and fix controller specs

spec/controllers/supplier/edit_spec.rb

@@ -1,7 +1,7 @@
 # encoding: UTF-8
 require 'spec_helper'
 
-describe SupplierController do
+describe SupplierController, type: :controller do
   before :each do
     @supplier = Supplier.find_by_email('supplier@qwaiter.com') || Supplier.create(name: 'Supplier', email: 'supplier@qwaiter.com', password: 'secret')
     sign_in @supplier