symbolize smtp_authentication setting to conform to rails docs

config/application.yml.example

@@ -137,8 +137,8 @@ defaults: &defaults
   # Set this to true if you want to use exim and sendmail
   sendmail_exim_fix: false
 
-  # Authentication required to send mail. Use one of 'one', 'plain',
-  # 'login' or 'cram-md5'. Use 'none' if server does not support
+  # Authentication required to send mail. Use one of 'plain',
+  # 'login' or 'cram_md5'. Use 'none' if server does not support
   # authentication
   smtp_authentication: 'plain'
 

config/initializers/mailer_config.rb

@@ -39,7 +39,7 @@ Diaspora::Application.configure do
           :address => AppConfig[:smtp_address],
           :port => AppConfig[:smtp_port],
           :domain => AppConfig[:smtp_domain],
-          :authentication => AppConfig[:smtp_authentication],
+          :authentication => AppConfig[:smtp_authentication].gsub('-', '_').to_s,
           :user_name => AppConfig[:smtp_username],
           :password => AppConfig[:smtp_password],
           :enable_starttls_auto => AppConfig[:smtp_starttls_auto],