Fix active tab test for branches page

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

features/steps/project/active_tab.rb

@@ -54,7 +54,7 @@ class Spinach::Features::ProjectActiveTab < Spinach::FeatureSteps
   end
   step 'I click the "Branches" tab' do
-    page.within '.content' do
+    page.within '.sub-nav' do
       click_link('Branches')
     end
   end