Update specs to new rspec syntax

spec/controllers/application_controller_spec.rb

@@ -6,7 +6,7 @@ describe ApplicationController do
   describe '#current_user=' do
     it 'stores the user id in the session as :user_id' do
       controller.current_user = user
-      session[:user_id].should == user.id
+      expect(session[:user_id]).to eq user.id
     end
   end
 
@@ -14,7 +14,7 @@ describe ApplicationController do
     context 'when session[:user_id] is set' do
       it 'returns the User instance from the session' do
         session[:user_id] = user.id
-        controller.current_user.should == user
+        expect(controller.current_user).to eq user
       end
     end
   end