Fixes #5172: Run the ncf api as the ncf-api user instead of the httpd on...

...e

Ticket: http://www.rudder-project.org/redmine/issues/5172

To be merged in 2.11
Why remove the ```threads=5``` argument? The doc says:
> If this option is not defined then the default will be to create 15 threads in each daemon process within the process group.

This seems a lot! Let's keep it at 5.