bgp: add neighbor_state_get method
bgp: add neighbor_state_get method

Can be used to get the state of peer(s).

Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

Zouyiran/ryu,iwaseyusuke/ryu,shinpeimuraoka/ryu,ttsubo/ryu,osrg/ryu,OpenState-SDN/ryu,hisaharu/ryu,habibiefaried/ryu,shinpeimuraoka/ryu,elahejalalpour/ELRyu,alanquillin/ryu,TakeshiTseng/ryu,ttsubo/ryu,StephenKing/ryu,osrg/ryu,elahejalalpour/ELRyu,elahejalalpour/ELRyu,fkakuma/ryu,OpenState-SDN/ryu,lagopus/ryu-lagopus-ext,alanquillin/ryu,takahashiminoru/ryu,pichuang/ryu,Tejas-Subramanya/RYU_MEC,TakeshiTseng/ryu,fujita/ryu,ttsubo/ryu,gareging/SDN_Framework,zangree/ryu,fujita/ryu,zangree/ryu,hisaharu/ryu,alanquillin/ryu,zangree/ryu,fujita/ryu,Tejas-Subramanya/RYU_MEC,TakeshiTseng/ryu,takahashiminoru/ryu,osrg/ryu,hisaharu/ryu,gareging/SDN_Framework,shinpeimuraoka/ryu,elahejalalpour/ELRyu,zyq001/ryu,TakeshiTseng/ryu,lagopus/ryu-lagopus-ext,fkakuma/ryu,Zouyiran/ryu,Zouyiran/ryu,StephenKing/ryu,zangree/ryu,darjus-amzn/ryu,John-Lin/ryu,lagopus/ryu-lagopus-ext,darjus-amzn/ryu,alanquillin/ryu,OpenState-SDN/ryu,habibiefaried/ryu,takahashiminoru/ryu,takahashiminoru/ryu,zyq001/ryu,hisaharu/ryu,OpenState-SDN/ryu,Tejas-Subramanya/RYU_MEC,zangree/ryu,alanquillin/ryu,ttsubo/ryu,habibiefaried/ryu,darjus-amzn/ryu,John-Lin/ryu,John-Lin/ryu,Zouyiran/ryu,gareging/SDN_Framework,Tejas-Subramanya/RYU_MEC,ttsubo/ryu,StephenKing/ryu,zyq001/ryu,habibiefaried/ryu,habibiefaried/ryu,elahejalalpour/ELRyu,fujita/ryu,iwaseyusuke/ryu,StephenKing/ryu,zyq001/ryu,pichuang/ryu,pichuang/ryu,Tejas-Subramanya/RYU_MEC,Zouyiran/ryu,TakeshiTseng/ryu,fujita/ryu,lagopus/ryu-lagopus-ext,John-Lin/ryu,StephenKing/ryu,shinpeimuraoka/ryu,hisaharu/ryu,pichuang/ryu,iwaseyusuke/ryu,osrg/ryu,pichuang/ryu,fkakuma/ryu,iwaseyusuke/ryu,darjus-amzn/ryu,gareging/SDN_Framework,lagopus/ryu-lagopus-ext,gareging/SDN_Framework,shinpeimuraoka/ryu,zyq001/ryu,darjus-amzn/ryu,osrg/ryu,OpenState-SDN/ryu,takahashiminoru/ryu,iwaseyusuke/ryu,fkakuma/ryu,John-Lin/ryu,fkakuma/ryu