Add tests for group active tab

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

features/group_active_tab.feature

+Feature: Group Active Tab
+  Background:
+    Given I sign in as "John Doe"
+    And "John Doe" is owner of group "Owned"
+    When I visit group "Owned" settings page
+
+  Scenario: On Audit events
+    When I go to "Audit Events"
+    Then the active sub nav should be Audit Events
+    And no other sub navs should be active
+    And the active main tab should be Settings
+
+  Scenario: On Web Hooks
+    When I go to "Web Hooks"
+    Then the active sub nav should be Web Hooks
+    And no other sub navs should be active
+    And the active main tab should be Settings
+

features/steps/group_active_tab.rb

+class Spinach::Features::GroupActiveTab < Spinach::FeatureSteps
+  include SharedAuthentication
+  include SharedUser
+  include SharedGroup
+  include SharedPaths
+  include SharedActiveTab
+
+  step 'the active sub nav should be Audit Events' do
+    ensure_active_sub_nav('Audit Events')
+  end
+
+  step 'the active main tab should be Settings' do
+    page.within '.nav-sidebar' do
+      expect(page).to have_content('Back to group')
+    end
+  end
+
+  step 'the active sub nav should be Web Hooks' do
+    ensure_active_sub_nav('Web Hooks')
+  end
+
+  step 'I go to "Audit Events"' do
+    click_link 'Audit Events'
+  end
+
+  step 'I go to "Web Hooks"' do
+    click_link 'Web Hooks'
+  end
+end