Rename "News Feed" buttons to "Activity Feed"

app/views/dashboard/_activities.html.haml

@@ -5,7 +5,7 @@
     %li.pull-right
       = link_to dashboard_path(:atom, { private_token: current_user.private_token }), class: 'rss-btn' do
         %i.fa.fa-rss
-        News Feed
+        Activity Feed
         
 = render 'shared/event_filter'
 %hr

app/views/groups/show.html.haml

@@ -23,7 +23,7 @@
             %li
               = link_to group_path(@group, { format: :atom, private_token: current_user.private_token }), title: "Feed", class: 'rss-btn' do
                 %i.fa.fa-rss
-                News Feed
+                Activity Feed
 
         = render 'shared/event_filter'
         %hr

app/views/projects/show.html.haml

@@ -49,7 +49,7 @@
             %li
               = link_to namespace_project_path(@project.namespace, @project, format: :atom, private_token: current_user.private_token), title: "Feed", class: 'rss-btn' do
                 %i.fa.fa-rss
-                News Feed
+                Activity Feed
 
         = render 'shared/event_filter'
         %hr