Merge chroot for interpreters RFE

In 2010 @dennmart implemented a patch for interpreters which allow
them to chroot. This patch was provided in:

http://code.google.com/p/cherokee/issues/detail?id=767 (GitHub #646)

Thanks a million for giving us a reference!
Update the documentation numbers, and phase.
Merge pull request #1054 from cherokee/sources_chroot

Sources chroot