nixos/gitlab: fixes

- fix timezone data not found
- fix module, add simple test
- allow to set port

pkgs/applications/version-management/gitlab/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, ruby, rubyLibs, libxslt, libxml2, pkgconfig, libffi, postgresql, libyaml, ncurses, curl, openssh, redis, zlib, icu, checkinstall, logrotate, docutils, cmake, git, gdbm, readline, unzip, gnumake, which }:
+{ stdenv, fetchurl, ruby, rubyLibs, libiconv, libxslt, libxml2, pkgconfig, libffi, postgresql, libyaml, ncurses, curl, openssh, redis, zlib, icu, checkinstall, logrotate, docutils, cmake, git, gdbm, readline, unzip, gnumake, which, tzdata }:
 
 let
   gemspec = map (gem: fetchurl { url=gem.url; sha256=gem.hash; }) (import ./Gemfile.nix);
@@ -61,6 +61,10 @@ in stdenv.mkDerivation rec {
     # See https://github.com/gitlabhq/gitlab-public-wiki/wiki/Trouble-Shooting-Guide:
     bundle install -j4 --verbose --local --deployment --without development test mysql
 
+    # Fix timezone data directory
+    substituteInPlace $out/share/gitlab/vendor/bundle/ruby/*/gems/tzinfo-*/lib/tzinfo/zoneinfo_data_source.rb \
+      --replace "/etc/zoneinfo" "${tzdata}/share/zoneinfo"
+
     # For reasons I don't understand "bundle exec" ignores the
     # RAILS_ENV causing tests to be executed that fail because we're
     # not installing development and test gems above. Deleting the