Merge branch 'changelog-link' into 'master'

Add changelog, license and contribution guide links to project sidebar.

If the version is known, the "Version: 7.9.0pre" button links to the changelog, otherwise a "View changelog" button is shown.

![Screen_Shot_2015-03-18_at_14.22.29](https://dev.gitlab.org/gitlab/gitlabhq/uploads/747acc018ec9a188098e0f0bc4e91cc3/Screen_Shot_2015-03-18_at_14.22.29.png)

See merge request !1708

1 files changed, 22 insertions, 2 deletions

diff --git a/app/models/repository.rb b/app/models/repository.rb
index 7addbca8fb1..c6eaa485b8a 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -122,7 +122,7 @@ class Repository
 
   def expire_cache
     %i(size branch_names tag_names commit_count graph_log
-       readme version contribution_guide).each do |key|
+       readme version contribution_guide changelog license).each do |key|
       cache.expire(key)
     end
   end
@@ -211,7 +211,27 @@ class Repository
   end
 
   def contribution_guide
-    cache.fetch(:contribution_guide) { tree(:head).contribution_guide }
+    cache.fetch(:contribution_guide) do
+      tree(:head).blobs.find do |file|
+        file.contributing?
+      end
+    end
+  end
+
+  def changelog
+    cache.fetch(:changelog) do
+      tree(:head).blobs.find do |file|
+        file.name =~ /^(changelog|history)/i
+      end
+    end
+  end
+
+  def license
+    cache.fetch(:license) do
+      tree(:head).blobs.find do |file|
+        file.name =~ /^license/i
+      end
+    end
   end
 
   def head_commit