netbase: split up in netbase and init-ifupdown

- netbase should only include etc-rpc, etc-protocols, etc-services
and the hosts file
- the init script/configuration files should be in another package
(init-ifupdown)

[YOCTO #2486]

Signed-off-by: Constantin Musca <constantinx.musca@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>