table: remove CoreService, Neighbors, and Commons structures

No need.

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

It's not necessary for our first target (multi RIB route server).

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

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