RyuApp: add a method to unregister a handler
RyuApp: add a method to unregister a handler

this method undos register_handler.

Signed-off-by: YAMAMOTO Takashi <458bba2e4a8704776b33478100c98529b639cd9e@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

StephenKing/ryu,zangree/ryu,iwaseyusuke/ryu,ynkjm/ryu,diogommartins/ryu,darjus-amzn/ryu,lsqtongxin/ryu,John-Lin/ryu,ysywh/ryu,OpenState-SDN/ryu,yamt/ryu,zyq001/ryu,Tejas-Subramanya/RYU_MEC,zangree/ryu,StephenKing/ryu,fujita/ryu,ysywh/ryu,osrg/ryu,takahashiminoru/ryu,shinpeimuraoka/ryu,jalilm/ryu,ntts-clo/ryu,TakeshiTseng/ryu,lzppp/mylearning,evanscottgray/ryu,gopchandani/ryu,alanquillin/ryu,lagopus/ryu-lagopus-ext,muzixing/ryu,lsqtongxin/ryu,elahejalalpour/ELRyu,OpenState-SDN/ryu,ysywh/ryu,zyq001/ryu,muzixing/ryu,StephenKing/ryu,Tesi-Luca-Davide/ryu,fkakuma/ryu,jkoelker/ryu,Zouyiran/ryu,sivaramakrishnansr/ryu,StephenKing/summerschool-2015-ryu,pichuang/ryu,John-Lin/ryu,umkcdcrg01/ryu_openflow,torufuru/oolhackathon,jalilm/ryu,StephenKing/summerschool-2015-ryu,ynkjm/ryu,habibiefaried/ryu,ttsubo/ryu,John-Lin/ryu,darjus-amzn/ryu,alanquillin/ryu,fkakuma/ryu,StephenKing/summerschool-2015-ryu,elahejalalpour/ELRyu,ttsubo/ryu,takahashiminoru/ryu,hisaharu/ryu,umkcdcrg01/ryu_openflow,umkcdcrg01/ryu_openflow,alanquillin/ryu,shinpeimuraoka/ryu,hisaharu/ryu,Tejas-Subramanya/RYU_MEC,diogommartins/ryu,muzixing/ryu,lzppp/mylearning,John-Lin/ryu,lzppp/mylearning,gopchandani/ryu,pichuang/ryu,Zouyiran/ryu,jalilm/ryu,ttsubo/ryu,zangree/ryu,darjus-amzn/ryu,alyosha1879/ryu,elahejalalpour/ELRyu,Tesi-Luca-Davide/ryu,zangree/ryu,zangree/ryu,habibiefaried/ryu,ntts-clo/ryu,torufuru/oolhackathon,Tesi-Luca-Davide/ryu,iwaseyusuke/ryu,lsqtongxin/ryu,ynkjm/ryu,alanquillin/ryu,osrg/ryu,openvapour/ryu,gopchandani/ryu,Tesi-Luca-Davide/ryu,lagopus/ryu-lagopus-ext,ynkjm/ryu,jazzmes/ryu,StephenKing/ryu,openvapour/ryu,lsqtongxin/ryu,jalilm/ryu,yamt/ryu,yamada-h/ryu,shinpeimuraoka/ryu,ynkjm/ryu,muzixing/ryu,lsqtongxin/ryu,yamt/ryu,TakeshiTseng/ryu,elahejalalpour/ELRyu,darjus-amzn/ryu,habibiefaried/ryu,osrg/ryu,StephenKing/summerschool-2015-ryu,alanquillin/ryu,Zouyiran/ryu,alyosha1879/ryu,jazzmes/ryu,StephenKing/ryu,diogommartins/ryu,OpenState-SDN/ryu,pichuang/ryu,iwaseyusuke/ryu,TakeshiTseng/ryu,yamt/ryu,haniehrajabi/ryu,alyosha1879/ryu,sivaramakrishnansr/ryu,jalilm/ryu,ttsubo/ryu,evanscottgray/ryu,shinpeimuraoka/ryu,openvapour/ryu,sivaramakrishnansr/ryu,hisaharu/ryu,shinpeimuraoka/ryu,pichuang/ryu,haniehrajabi/ryu,evanscottgray/ryu,torufuru/oolhackathon,Tejas-Subramanya/RYU_MEC,umkcdcrg01/ryu_openflow,jazzmes/ryu,TakeshiTseng/ryu,StephenKing/summerschool-2015-ryu,hisaharu/ryu,haniehrajabi/ryu,lagopus/ryu-lagopus-ext,gareging/SDN_Framework,gopchandani/ryu,gareging/SDN_Framework,habibiefaried/ryu,openvapour/ryu,gareging/SDN_Framework,ntts-clo/mld-ryu,lagopus/ryu-lagopus-ext,alyosha1879/ryu,lzppp/mylearning,lzppp/mylearning,haniehrajabi/ryu,pichuang/ryu,takahashiminoru/ryu,osrg/ryu,yamada-h/ryu,Zouyiran/ryu,fujita/ryu,lagopus/ryu-lagopus-ext,iwaseyusuke/ryu,haniehrajabi/ryu,Tesi-Luca-Davide/ryu,umkcdcrg01/ryu_openflow,gareging/SDN_Framework,takahashiminoru/ryu,ysywh/ryu,openvapour/ryu,OpenState-SDN/ryu,gareging/SDN_Framework,castroflavio/ryu,zyq001/ryu,ysywh/ryu,castroflavio/ryu,Zouyiran/ryu,fkakuma/ryu,ttsubo/ryu,Tejas-Subramanya/RYU_MEC,fkakuma/ryu,gopchandani/ryu,habibiefaried/ryu,fujita/ryu,zyq001/ryu,osrg/ryu,diogommartins/ryu,zyq001/ryu,jkoelker/ryu,o3project/ryu-oe,elahejalalpour/ELRyu,iwaseyusuke/ryu,diogommartins/ryu,o3project/ryu-oe,muzixing/ryu,OpenState-SDN/ryu,fkakuma/ryu,TakeshiTseng/ryu,darjus-amzn/ryu,ntts-clo/mld-ryu,yamt/ryu,hisaharu/ryu,takahashiminoru/ryu,sivaramakrishnansr/ryu,castroflavio/ryu,sivaramakrishnansr/ryu,fujita/ryu,John-Lin/ryu,jkoelker/ryu,fujita/ryu,Tejas-Subramanya/RYU_MEC