Set the temp directory for Roundcube, related to #365

(cherry picked from commit 34d88144b2)

webmails/roundcube/config.inc.php

@@ -4,6 +4,7 @@ $config = array();
 
 // Generals
 $config['db_dsnw'] = 'sqlite:////data/roundcube.db';
+$config['temp_dir'] = '/tmp/';
 $config['des_key'] = getenv('SECRET_KEY');
 $config['identities_level'] = 3;
 $config['reply_all_mode'] = 1;