Must use Lwt_unix.fork instead of Unix.fork

If ocsigenserver is daemonized, and it does something with Lwt prior to forking
then it will deadlock.

To reproduce set an invalid hostname for example, and see that it fails to bind
to the port:
$ sudo hostname invalid
$ sudo `opam config var bin`/ocsigenserver.opt  --daemon
ocsigenserver.opt: main: Cannot determine default host name. Will use "invalid" to create absolute links or redirections dynamically if you do not set <host defaulthostname="..." ...> in config file.
$ sudo netstat -ntpa|grep ocsi

This is because printing the error message uses Lwt, and then you cannot use
Unix.fork without resetting Lwt after the fork!

Set good hostname again and it works:
$ sudo hostname <good-hostname>
$ sudo `opam config var bin`/ocsigenserver.opt  --daemon
$ sudo netstat -ntpa|grep ocsi
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      15288/ocsigenserver
tcp6       0      0 :::80                   :::*                    LISTEN      15288/ocsigenserver
Hidden request_info
Forget request_info
Hidden response
Apply hidden type on deflatemod extension
Remove warning
Fix compilation
Refix compilation
I don't want to install camlzip
Add accept_encoding accessor of request_info
Merge pull request #27 from edwintorok/forkfix

Must use Lwt_unix.fork instead of Unix.fork
No alias (change RI to Ocsigen_request_info)
Fix error (Ocsigen_resquest_info to Ocsigen_request_info)
Merge pull request #33 from dinosaure/hidden-type

Hidden type
Remove non-exhaustive pattern-matching warning
Adding option <sethttpcode> in outputfilter
Removing indentation with tabs in outputfilter.ml
Adding option continue to rewritemod, to continue with rewritten request (instead of restarting)
Doc: new options in outputfilter and rewritemod
Raise an error to parse syslog facility