Upgrade to net-ldap 0.3.1 (#10272).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@8908 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -7,7 +7,7 @@ gem "fastercsv", "~> 1.5.0", :platforms => [:mri_18, :mingw_18, :jruby]
 
 # Optional gem for LDAP authentication
 group :ldap do
-  gem "net-ldap", "~> 0.2.2"
+  gem "net-ldap", "~> 0.3.1"
 end
 
 # Optional gem for OpenID authentication