bgp: set bgp-config-file default None
bgp: set bgp-config-file default None

allowing not use a config file.

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

fkakuma/ryu,elahejalalpour/ELRyu,elahejalalpour/ELRyu,fkakuma/ryu,Tesi-Luca-Davide/ryu,gopchandani/ryu,fkakuma/ryu,haniehrajabi/ryu,torufuru/oolhackathon,Tesi-Luca-Davide/ryu,John-Lin/ryu,OpenState-SDN/ryu,torufuru/oolhackathon,fujita/ryu,jalilm/ryu,lsqtongxin/ryu,ysywh/ryu,lagopus/ryu-lagopus-ext,jkoelker/ryu,sivaramakrishnansr/ryu,castroflavio/ryu,John-Lin/ryu,ttsubo/ryu,lzppp/mylearning,TakeshiTseng/ryu,John-Lin/ryu,lzppp/mylearning,fujita/ryu,John-Lin/ryu,TakeshiTseng/ryu,OpenState-SDN/ryu,ysywh/ryu,jazzmes/ryu,darjus-amzn/ryu,StephenKing/ryu,haniehrajabi/ryu,takahashiminoru/ryu,umkcdcrg01/ryu_openflow,pichuang/ryu,alanquillin/ryu,yamt/ryu,zyq001/ryu,StephenKing/ryu,jalilm/ryu,haniehrajabi/ryu,alyosha1879/ryu,jalilm/ryu,ttsubo/ryu,muzixing/ryu,shinpeimuraoka/ryu,alyosha1879/ryu,lsqtongxin/ryu,torufuru/oolhackathon,jkoelker/ryu,ttsubo/ryu,elahejalalpour/ELRyu,zangree/ryu,gareging/SDN_Framework,diogommartins/ryu,openvapour/ryu,StephenKing/ryu,alanquillin/ryu,zangree/ryu,ynkjm/ryu,hisaharu/ryu,ynkjm/ryu,openvapour/ryu,sivaramakrishnansr/ryu,yamt/ryu,lzppp/mylearning,ysywh/ryu,yamt/ryu,lagopus/ryu-lagopus-ext,StephenKing/ryu,zangree/ryu,lsqtongxin/ryu,Tejas-Subramanya/RYU_MEC,takahashiminoru/ryu,gareging/SDN_Framework,zyq001/ryu,jalilm/ryu,lzppp/mylearning,muzixing/ryu,muzixing/ryu,umkcdcrg01/ryu_openflow,evanscottgray/ryu,John-Lin/ryu,yamt/ryu,TakeshiTseng/ryu,elahejalalpour/ELRyu,Tejas-Subramanya/RYU_MEC,zyq001/ryu,pichuang/ryu,habibiefaried/ryu,ynkjm/ryu,fkakuma/ryu,openvapour/ryu,lsqtongxin/ryu,zyq001/ryu,OpenState-SDN/ryu,Tejas-Subramanya/RYU_MEC,hisaharu/ryu,TakeshiTseng/ryu,ttsubo/ryu,alanquillin/ryu,gopchandani/ryu,gareging/SDN_Framework,Zouyiran/ryu,ynkjm/ryu,pichuang/ryu,castroflavio/ryu,habibiefaried/ryu,shinpeimuraoka/ryu,Tesi-Luca-Davide/ryu,lagopus/ryu-lagopus-ext,diogommartins/ryu,gopchandani/ryu,darjus-amzn/ryu,Zouyiran/ryu,zangree/ryu,zyq001/ryu,jazzmes/ryu,iwaseyusuke/ryu,Tejas-Subramanya/RYU_MEC,Zouyiran/ryu,StephenKing/ryu,fujita/ryu,darjus-amzn/ryu,darjus-amzn/ryu,alanquillin/ryu,TakeshiTseng/ryu,takahashiminoru/ryu,Tesi-Luca-Davide/ryu,jalilm/ryu,ysywh/ryu,hisaharu/ryu,evanscottgray/ryu,osrg/ryu,jazzmes/ryu,ynkjm/ryu,diogommartins/ryu,hisaharu/ryu,diogommartins/ryu,ttsubo/ryu,gopchandani/ryu,umkcdcrg01/ryu_openflow,alyosha1879/ryu,sivaramakrishnansr/ryu,takahashiminoru/ryu,OpenState-SDN/ryu,Zouyiran/ryu,gareging/SDN_Framework,lzppp/mylearning,OpenState-SDN/ryu,iwaseyusuke/ryu,shinpeimuraoka/ryu,takahashiminoru/ryu,Zouyiran/ryu,lagopus/ryu-lagopus-ext,darjus-amzn/ryu,hisaharu/ryu,yamt/ryu,osrg/ryu,habibiefaried/ryu,jkoelker/ryu,Tesi-Luca-Davide/ryu,diogommartins/ryu,Tejas-Subramanya/RYU_MEC,StephenKing/summerschool-2015-ryu,gopchandani/ryu,openvapour/ryu,StephenKing/summerschool-2015-ryu,shinpeimuraoka/ryu,osrg/ryu,umkcdcrg01/ryu_openflow,shinpeimuraoka/ryu,habibiefaried/ryu,fujita/ryu,lagopus/ryu-lagopus-ext,iwaseyusuke/ryu,alanquillin/ryu,pichuang/ryu,gareging/SDN_Framework,zangree/ryu,umkcdcrg01/ryu_openflow,ysywh/ryu,muzixing/ryu,haniehrajabi/ryu,fkakuma/ryu,lsqtongxin/ryu,StephenKing/summerschool-2015-ryu,StephenKing/summerschool-2015-ryu,iwaseyusuke/ryu,haniehrajabi/ryu,fujita/ryu,iwaseyusuke/ryu,openvapour/ryu,sivaramakrishnansr/ryu,castroflavio/ryu,sivaramakrishnansr/ryu,pichuang/ryu,muzixing/ryu,osrg/ryu,evanscottgray/ryu,habibiefaried/ryu,osrg/ryu,elahejalalpour/ELRyu,alyosha1879/ryu,StephenKing/summerschool-2015-ryu