tox.ini: Be able to run python3 unit tests
tox.ini: Be able to run python3 unit tests

With this change, you can run "tox -e py34" to test python3 compatibility.

Signed-off-by: IWAMOTO Toshihiro <8e41ae29694291a01b8efca6b4a0005a87ddb93e@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

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