Hide gpg signature on tags page from tag message

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/helpers/git_helper.rb

+module GitHelper
+  def strip_gpg_signature(text)
+    text.gsub(/-----BEGIN PGP SIGNATURE-----(.*)-----END PGP SIGNATURE-----/m, "")
+  end
+end

app/views/projects/tags/_tag.html.haml

@@ -6,7 +6,7 @@
       = tag.name
     - if tag.message.present?
        
-      = tag.message
+      = strip_gpg_signature(tag.message)
     .pull-right
       - if can? current_user, :download_code, @project
         = render 'projects/repositories/download_archive', ref: tag.name, btn_class: 'btn-grouped btn-group-small'