Modified the maximum presentation size from 20mb to 30mb

git-svn-id: http://bigbluebutton.googlecode.com/svn/trunk@3362 af16638f-c34d-0410-8cfa-b39d5352b314

bigbluebutton-client/config/bigbluebutton.nginx

@@ -42,7 +42,7 @@ server {
            proxy_redirect     default;
            proxy_set_header   X-Forwarded-For   $proxy_add_x_forwarded_for;
 
-           client_max_body_size       20m;
+           client_max_body_size       30m;
            client_body_buffer_size    128k;
 
            proxy_connect_timeout      90;