app/rest: add requirements to path component

This patch adds requirements to path component so that URL is verified.
And simplify with submapper.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
app/rest_nw_id: add port type for reserved port and vport-gre

This patch adds new port type for reserved port and vport-gre.
They will be used later. Via this REST API, ryu knows which port is used
for gre or reserved port.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
ryu/app/client: factor out rest client code

REST API will be enhanced. So factor out reset client code such that
it affords extension.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
app/client: add helper function to ignore NOT_FOUND, 404

Sometimes client code just wants to ignore 404 when deleting resources.
So provide helper function for it.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
bin/ryu-manager: import ryu.flags for common options

Otherwise those options can't be specified.

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