Move nutcracker to sbin instead of bin

nutcracker is a daemon, so it obviously belongs to /usr/sbin, not
/usr/bin/.
Add a manpage

Add a nutcracker.8 manpage mostly based off nutcracker --help.
Merge pull request #125 from paravoid/manpage

Add a manpage
Merge pull request #124 from paravoid/move-to-sbin

Move nutcracker to sbin instead of bin