Default allow username or email login to false

-If not specified in the gitlab.yml default this setting to false

Change-Id: I3551df364498dd84ccbd18c90797522e77159f05

config/initializers/1_settings.rb

@@ -37,6 +37,8 @@ end
 # Default settings
 Settings['ldap'] ||= Settingslogic.new({})
 Settings.ldap['enabled'] = false if Settings.ldap['enabled'].nil?
+Settings.ldap['allow_username_or_email_login'] = false if Settings.ldap['allow_username_or_email_login'].nil?
+
 Settings['omniauth'] ||= Settingslogic.new({})
 Settings.omniauth['enabled']      = false if Settings.omniauth['enabled'].nil?