Refactor LDAP config

* Move credentials to ENV vars in prod
* Use same configs in dev and prod
* Make UID attribute and admin DN configurable

config/initializers/devise.rb

@@ -45,7 +45,7 @@ Devise.setup do |config|
   # Configure the e-mail address which will be shown in Devise::Mailer,
   # note that it will be overwritten if you use your own mailer class
   # with default "from" parameter.
-  config.mailer_sender = 'accounts@kosmos.org'
+  config.mailer_sender = ENV["SMTP_FROM_ADDRESS"] || 'accounts@localhost'
 
   # Configure the class responsible to send e-mails.
   # config.mailer = 'Devise::Mailer'