UX improvements

• make atom feed on commits page smaller so it capture less attention
• open big image 400px instead of default 40px when click on user avatar

app/views/users/show.html.haml

@@ -9,7 +9,7 @@
 .row
   %section.col-md-8
     .header-with-avatar
-      = link_to avatar_icon(@user.email), target: '_blank' do
+      = link_to avatar_icon(@user.email, 400), target: '_blank' do
         = image_tag avatar_icon(@user.email, 90), class: "avatar avatar-tile s90", alt: ''
       %h3
         = @user.name