Fix Spinach login issues

This was caused by
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10320Signed-off-by: Rémy Coutable <remy@rymai.me>

features/steps/project/merge_requests.rb

@@ -673,8 +673,8 @@ class Spinach::Features::ProjectMergeRequests < Spinach::FeatureSteps
     project = Project.find_by(name: "Shop")
     project.team << [user, :developer]
 
-    logout
-    login_with user
+    gitlab_sign_out
+    sign_in(user)
   end
 
   step '"Bug NS-05" has CI status' do

features/steps/shared/authentication.rb

@@ -31,7 +31,7 @@ module SharedAuthentication
   end
 
   step 'I sign in as "Pete Peters"' do
-    login_with(user_exists("Pete Peters"))
+    gitlab_sign_in(user_exists("Pete Peters"))
   end
 
   step 'I should be redirected to sign in page' do