Added <link> tags to profiles and entries

app/views/layouts/application.html.haml

-!!!
+!!! 5
 %html
   %head
     %meta{:content => "text/html; charset=UTF-8", "http-equiv" => "Content-Type"}/
@@ -6,6 +6,7 @@
     = stylesheet_link_tag    'application', media: 'all'
     = javascript_include_tag 'application'
     = csrf_meta_tags
+    = yield :header_tags
   %body
     .container
       = yield

app/views/profile/entry.html.haml

-%div.activity-stream
+- content_for :header_tags do
+  %link{ rel: 'alternate', type: 'application/atom+xml', href: atom_entry_url(id: @entry.id) }/
+
+.activity-stream
   = render partial: @type, locals: { @type.to_sym => @entry.activity, include_threads: true, is_predecessor: false, is_successor: false }

app/views/profile/show.html.haml

+- content_for :header_tags do
+  %link{ rel: 'salmon', href: salmon_url(@account) }/
+  %link{ rel: 'alternate', type: 'application/atom+xml', href: atom_user_stream_url(id: @account.id) }/
+
 .card
   .avatar= image_tag @account.avatar.url(:medium)
   .bio