This fixes multiple issues like upload/download problems on seahub
and also makes it possible to use the new HTTP syncing feature
which doesn't work with libevhtp 1.2.10 at all.
* Use the correct path for the pidfile
* Start a multithreaded daemon instead of pre-forking worker processes.
This avoids consuming too much memory and makes context switches faster
Signed-off-by: Gergely Kiss <mail.gery@gmail.com>