fix syslogd usage on OSX

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
allow application to specify its logger name

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
of12: set default attributes for OFPStatsRequest subclasses

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
of13: set default attributes for OFPMultipartRequest subclasses

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Ryu 3.6

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>