Added support for Go's repository retrieval.

 - Simply adds the releavant meta link in the project's show action.
 - Information about this meta tag can be found here:
   http://golang.org/cmd/go/#hdr-Remote_import_paths

app/views/layouts/_head.html.haml

 %head
   %meta{charset: "utf-8"}
+
+  -# Go repository retrieval support.
+  - if controller_name == 'projects' && action_name == 'show'
+    %meta{name: "go-import", content: "#{Gitlab.config.gitlab.host}/#{@project.namespace.path}/#{@project.path} git http://#{Gitlab.config.gitlab.host}/#{@project.namespace.path}/#{@project.path}.git"}
+
   %title
     = "#{title} | " if defined?(title)
     GitLab