gitlab: Sync gitlab-parameters.cfg to upstream

I've manually reviewed

    git diff 8.6.5+ce.0-0-g342f8be..8.7.9+ce.1-0-gf589ad7 --    \
        files/gitlab-config-template/gitlab.rb.template \
        files/gitlab-cookbooks/gitlab/attributes/default.rb

and modulo trusted proxies there are no interesting changes for us.

software/gitlab/gitlab-parameters.cfg

@@ -6,7 +6,7 @@
 #
 # TODO better autogenerate from ^^^ (?)
 #
-# (last updated for omnibus-gitlab 8.6.5+ce.0-0-g342f8be)
+# (last updated for omnibus-gitlab 8.7.9+ce.1-0-gf589ad7)
 
 [gitlab-parameters]
 configuration.external_url              = http://lab.example.com
@@ -101,3 +101,8 @@ configuration.nginx_gzip_comp_level     = 2
 configuration.nginx_gzip_proxied        = any
 configuration.nginx_gzip_types          = text/plain text/css application/x-javascript text/xml application/xml application/xml+rss text/javascript application/json
 configuration.nginx_keepalive_timeout   = 65
+
+# TODO allow configuring trusted proxies
+# configuration.nginx_real_ip_trusted_addresses
+# configuration.nginx_real_ip_header
+# configuration.nginx_real_ip_recursive

software/gitlab/software.cfg

@@ -232,7 +232,7 @@ md5sum  = eb1230fee50067924ba89f4dc6e82fa9
 
 [gitlab-parameters.cfg]
 <= download-file
-md5sum  = 8cbcdb8d9e942df67d2fbb4db5fbfaad
+md5sum  = 3edd435a984b51b94539ea1d4f1b3994
 
 [gitlab-shell-config.yml.in]
 <= download-template