pip-requires: gui_topology requires webob>=1.2

gui_topology imports webob.static.DirecoryApp
which was added since webob 1.2

Signed-off-by: Hisaharu Ishii <ishii.hisaharu@lab.ntt.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
bgp: support specifying nexthop per prefix

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
add --pid-file option to cli

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