makefile cosmetic

its not an error if there are no updates, so do not exit 1

Signed-off-by: Sven Nierlein <sven@consol.de>
don't enable shinken plugin by default

users which want to enable that, can still do that later manually.

Signed-off-by: Sven Nierlein <sven@consol.de>
install and build libnaemon and devel pkg

in order to make it easier for addon developers, we now provide
libnaemon and naemon headers in a seperate package which can be
used for addon building and packaging.

Signed-off-by: Sven Nierlein <sven@consol.de>