bgp/cli: show adjacency rib in/out by show neighbor commands

show neighbor sent-routes/received-routes commands used to show the
routes in local rib, but the right behavior is to show adjacency rib
in/out.

Signed-off-by: ISHIDA Wataru <ishida.wataru@lab.ntt.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
bgp: fix lacking import

Signed-off-by: ISHIDA Wataru <ishida.wataru@lab.ntt.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
bgp: enable to stop a chile thread by specifying its name

Signed-off-by: ISHIDA Wataru <ishida.wataru@lab.ntt.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
bgp: support connect modes to choose how to connect to the neighbors

three connect modes are supported

    CONNECT_MODE_ACTIVE: try to connect from us. don't listen
    CONNECT_MODE_PASSIVE: just listen
    CONNECT_MODE_BOTH: try both methods

dynamic change of connect modes is also supported

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