Allow Ruby client code to set a user agent
Allow Ruby client code to set a user agent

wcevans/grpc,geffzhang/grpc,andrewpollock/grpc,PeterFaiman/ruby-grpc-minimal,murgatroid99/grpc,philcleveland/grpc,LuminateWireless/grpc,PeterFaiman/ruby-grpc-minimal,bogdandrutu/grpc,pszemus/grpc,pmarks-net/grpc,fuchsia-mirror/third_party-grpc,a-veitch/grpc,yugui/grpc,malexzx/grpc,nicolasnoble/grpc,thinkerou/grpc,hstefan/grpc,donnadionne/grpc,makdharma/grpc,apolcyn/grpc,donnadionne/grpc,ppietrasa/grpc,LuminateWireless/grpc,makdharma/grpc,kpayson64/grpc,baylabs/grpc,sreecha/grpc,soltanmm-google/grpc,malexzx/grpc,MakMukhi/grpc,a-veitch/grpc,fuchsia-mirror/third_party-grpc,kpayson64/grpc,kriswuollett/grpc,leifurhauks/grpc,yang-g/grpc,Crevil/grpc,muxi/grpc,bogdandrutu/grpc,firebase/grpc,apolcyn/grpc,rjshade/grpc,adelez/grpc,dklempner/grpc,jcanizales/grpc,mehrdada/grpc,soltanmm/grpc,kskalski/grpc,pszemus/grpc,yang-g/grpc,carl-mastrangelo/grpc,pszemus/grpc,wcevans/grpc,makdharma/grpc,nicolasnoble/grpc,LuminateWireless/grpc,pmarks-net/grpc,jtattermusch/grpc,donnadionne/grpc,murgatroid99/grpc,malexzx/grpc,deepaklukose/grpc,carl-mastrangelo/grpc,royalharsh/grpc,daniel-j-born/grpc,thunderboltsid/grpc,grani/grpc,tengyifei/grpc,nicolasnoble/grpc,muxi/grpc,jboeuf/grpc,perumaalgoog/grpc,pmarks-net/grpc,vsco/grpc,Crevil/grpc,kskalski/grpc,makdharma/grpc,thunderboltsid/grpc,jboeuf/grpc,chrisdunelm/grpc,y-zeng/grpc,thinkerou/grpc,yugui/grpc,philcleveland/grpc,hstefan/grpc,grpc/grpc,thinkerou/grpc,jcanizales/grpc,philcleveland/grpc,soltanmm/grpc,ncteisen/grpc,chrisdunelm/grpc,sreecha/grpc,kumaralokgithub/grpc,grpc/grpc,kumaralokgithub/grpc,pszemus/grpc,firebase/grpc,jtattermusch/grpc,LuminateWireless/grpc,thinkerou/grpc,firebase/grpc,kumaralokgithub/grpc,geffzhang/grpc,7anner/grpc,jtattermusch/grpc,goldenbull/grpc,wcevans/grpc,dgquintas/grpc,fuchsia-mirror/third_party-grpc,MakMukhi/grpc,jcanizales/grpc,ejona86/grpc,kskalski/grpc,zhimingxie/grpc,podsvirov/grpc,dklempner/grpc,podsvirov/grpc,tengyifei/grpc,grani/grpc,mehrdada/grpc,kpayson64/grpc,simonkuang/grpc,zhimingxie/grpc,nicolasnoble/grpc,nicolasnoble/grpc,adelez/grpc,perumaalgoog/grpc,LuminateWireless/grpc,yang-g/grpc,jcanizales/grpc,yang-g/grpc,andrewpollock/grpc,ejona86/grpc,chrisdunelm/grpc,leifurhauks/grpc,andrewpollock/grpc,yongni/grpc,kumaralokgithub/grpc,royalharsh/grpc,nicolasnoble/grpc,Vizerai/grpc,jboeuf/grpc,tengyifei/grpc,ipylypiv/grpc,ctiller/grpc,geffzhang/grpc,geffzhang/grpc,PeterFaiman/ruby-grpc-minimal,fuchsia-mirror/third_party-grpc,thunderboltsid/grpc,yang-g/grpc,dklempner/grpc,jboeuf/grpc,bogdandrutu/grpc,donnadionne/grpc,apolcyn/grpc,nicolasnoble/grpc,malexzx/grpc,LuminateWireless/grpc,vjpai/grpc,kumaralokgithub/grpc,geffzhang/grpc,stanley-cheung/grpc,deepaklukose/grpc,Vizerai/grpc,ctiller/grpc,kriswuollett/grpc,ejona86/grpc,mehrdada/grpc,thinkerou/grpc,pszemus/grpc,a-veitch/grpc,7anner/grpc,grpc/grpc,soltanmm-google/grpc,tengyifei/grpc,soltanmm-google/grpc,geffzhang/grpc,daniel-j-born/grpc,ipylypiv/grpc,simonkuang/grpc,yugui/grpc,stanley-cheung/grpc,infinit/grpc,wcevans/grpc,thunderboltsid/grpc,stanley-cheung/grpc,grpc/grpc,stanley-cheung/grpc,podsvirov/grpc,7anner/grpc,vjpai/grpc,kpayson64/grpc,malexzx/grpc,vjpai/grpc,sreecha/grpc,makdharma/grpc,hstefan/grpc,simonkuang/grpc,muxi/grpc,daniel-j-born/grpc,dgquintas/grpc,adelez/grpc,sreecha/grpc,vsco/grpc,greasypizza/grpc,podsvirov/grpc,baylabs/grpc,a11r/grpc,jboeuf/grpc,carl-mastrangelo/grpc,ppietrasa/grpc,msmania/grpc,goldenbull/grpc,perumaalgoog/grpc,goldenbull/grpc,carl-mastrangelo/grpc,daniel-j-born/grpc,sreecha/grpc,greasypizza/grpc,fuchsia-mirror/third_party-grpc,vjpai/grpc,fuchsia-mirror/third_party-grpc,yongni/grpc,nicolasnoble/grpc,stanley-cheung/grpc,pmarks-net/grpc,yang-g/grpc,adelez/grpc,zhimingxie/grpc,msmania/grpc,jboeuf/grpc,firebase/grpc,kpayson64/grpc,philcleveland/grpc,arkmaxim/grpc,thunderboltsid/grpc,7anner/grpc,perumaalgoog/grpc,vsco/grpc,pmarks-net/grpc,jtattermusch/grpc,sreecha/grpc,kumaralokgithub/grpc,a11r/grpc,sreecha/grpc,apolcyn/grpc,a11r/grpc,daniel-j-born/grpc,leifurhauks/grpc,muxi/grpc,infinit/grpc,thunderboltsid/grpc,ctiller/grpc,daniel-j-born/grpc,Crevil/grpc,MakMukhi/grpc,carl-mastrangelo/grpc,msmania/grpc,tengyifei/grpc,royalharsh/grpc,andrewpollock/grpc,vjpai/grpc,rjshade/grpc,makdharma/grpc,podsvirov/grpc,ctiller/grpc,quizlet/grpc,a11r/grpc,makdharma/grpc,murgatroid99/grpc,ncteisen/grpc,a-veitch/grpc,7anner/grpc,andrewpollock/grpc,ppietrasa/grpc,simonkuang/grpc,yang-g/grpc,hstefan/grpc,dgquintas/grpc,greasypizza/grpc,matt-kwong/grpc,PeterFaiman/ruby-grpc-minimal,yugui/grpc,vsco/grpc,perumaalgoog/grpc,zhimingxie/grpc,PeterFaiman/ruby-grpc-minimal,ppietrasa/grpc,mehrdada/grpc,kskalski/grpc,tengyifei/grpc,MakMukhi/grpc,royalharsh/grpc,grani/grpc,wcevans/grpc,chrisdunelm/grpc,thinkerou/grpc,jtattermusch/grpc,matt-kwong/grpc,quizlet/grpc,philcleveland/grpc,thinkerou/grpc,soltanmm/grpc,vsco/grpc,fuchsia-mirror/third_party-grpc,dgquintas/grpc,ppietrasa/grpc,Crevil/grpc,Vizerai/grpc,kskalski/grpc,perumaalgoog/grpc,ejona86/grpc,jtattermusch/grpc,jtattermusch/grpc,nicolasnoble/grpc,adelez/grpc,soltanmm-google/grpc,kpayson64/grpc,jcanizales/grpc,philcleveland/grpc,quizlet/grpc,infinit/grpc,soltanmm/grpc,Crevil/grpc,ctiller/grpc,PeterFaiman/ruby-grpc-minimal,MakMukhi/grpc,MakMukhi/grpc,zhimingxie/grpc,pszemus/grpc,adelez/grpc,vsco/grpc,goldenbull/grpc,malexzx/grpc,deepaklukose/grpc,matt-kwong/grpc,dgquintas/grpc,grani/grpc,ncteisen/grpc,hstefan/grpc,muxi/grpc,ctiller/grpc,kskalski/grpc,leifurhauks/grpc,kpayson64/grpc,soltanmm-google/grpc,greasypizza/grpc,bogdandrutu/grpc,goldenbull/grpc,mehrdada/grpc,y-zeng/grpc,grpc/grpc,quizlet/grpc,royalharsh/grpc,bogdandrutu/grpc,7anner/grpc,sreecha/grpc,donnadionne/grpc,ctiller/grpc,arkmaxim/grpc,wcevans/grpc,ctiller/grpc,firebase/grpc,thunderboltsid/grpc,dgquintas/grpc,vjpai/grpc,perumaalgoog/grpc,matt-kwong/grpc,dklempner/grpc,ejona86/grpc,yongni/grpc,thunderboltsid/grpc,quizlet/grpc,mehrdada/grpc,ejona86/grpc,tengyifei/grpc,firebase/grpc,vsco/grpc,andrewpollock/grpc,jcanizales/grpc,fuchsia-mirror/third_party-grpc,simonkuang/grpc,yongni/grpc,mehrdada/grpc,greasypizza/grpc,andrewpollock/grpc,a-veitch/grpc,bogdandrutu/grpc,simonkuang/grpc,a11r/grpc,pmarks-net/grpc,zhimingxie/grpc,carl-mastrangelo/grpc,arkmaxim/grpc,greasypizza/grpc,arkmaxim/grpc,goldenbull/grpc,apolcyn/grpc,goldenbull/grpc,tengyifei/grpc,stanley-cheung/grpc,ipylypiv/grpc,leifurhauks/grpc,rjshade/grpc,matt-kwong/grpc,ipylypiv/grpc,infinit/grpc,leifurhauks/grpc,grpc/grpc,ctiller/grpc,malexzx/grpc,ncteisen/grpc,podsvirov/grpc,LuminateWireless/grpc,quizlet/grpc,royalharsh/grpc,soltanmm-google/grpc,kpayson64/grpc,ncteisen/grpc,philcleveland/grpc,pmarks-net/grpc,jtattermusch/grpc,ppietrasa/grpc,wcevans/grpc,soltanmm-google/grpc,leifurhauks/grpc,murgatroid99/grpc,soltanmm-google/grpc,bogdandrutu/grpc,Crevil/grpc,y-zeng/grpc,jboeuf/grpc,apolcyn/grpc,ctiller/grpc,muxi/grpc,a-veitch/grpc,greasypizza/grpc,dgquintas/grpc,7anner/grpc,makdharma/grpc,quizlet/grpc,pszemus/grpc,rjshade/grpc,zhimingxie/grpc,arkmaxim/grpc,kumaralokgithub/grpc,infinit/grpc,soltanmm/grpc,kskalski/grpc,yugui/grpc,kumaralokgithub/grpc,stanley-cheung/grpc,adelez/grpc,kpayson64/grpc,y-zeng/grpc,muxi/grpc,rjshade/grpc,apolcyn/grpc,ppietrasa/grpc,bogdandrutu/grpc,perumaalgoog/grpc,apolcyn/grpc,infinit/grpc,donnadionne/grpc,yongni/grpc,ppietrasa/grpc,MakMukhi/grpc,dgquintas/grpc,murgatroid99/grpc,jtattermusch/grpc,7anner/grpc,a11r/grpc,baylabs/grpc,fuchsia-mirror/third_party-grpc,ipylypiv/grpc,carl-mastrangelo/grpc,yang-g/grpc,thunderboltsid/grpc,mehrdada/grpc,ncteisen/grpc,yongni/grpc,Vizerai/grpc,deepaklukose/grpc,sreecha/grpc,ncteisen/grpc,pszemus/grpc,daniel-j-born/grpc,donnadionne/grpc,nicolasnoble/grpc,ctiller/grpc,firebase/grpc,firebase/grpc,fuchsia-mirror/third_party-grpc,deepaklukose/grpc,carl-mastrangelo/grpc,vsco/grpc,grani/grpc,malexzx/grpc,grani/grpc,infinit/grpc,kriswuollett/grpc,chrisdunelm/grpc,a-veitch/grpc,grpc/grpc,muxi/grpc,yugui/grpc,chrisdunelm/grpc,chrisdunelm/grpc,muxi/grpc,yugui/grpc,mehrdada/grpc,matt-kwong/grpc,PeterFaiman/ruby-grpc-minimal,dgquintas/grpc,simonkuang/grpc,mehrdada/grpc,Vizerai/grpc,grpc/grpc,murgatroid99/grpc,a11r/grpc,ipylypiv/grpc,kriswuollett/grpc,jboeuf/grpc,goldenbull/grpc,Vizerai/grpc,kumaralokgithub/grpc,stanley-cheung/grpc,vsco/grpc,thinkerou/grpc,greasypizza/grpc,jcanizales/grpc,murgatroid99/grpc,baylabs/grpc,msmania/grpc,kpayson64/grpc,geffzhang/grpc,ipylypiv/grpc,murgatroid99/grpc,geffzhang/grpc,donnadionne/grpc,ncteisen/grpc,soltanmm/grpc,jtattermusch/grpc,deepaklukose/grpc,deepaklukose/grpc,dklempner/grpc,jboeuf/grpc,rjshade/grpc,murgatroid99/grpc,yongni/grpc,vjpai/grpc,pszemus/grpc,hstefan/grpc,y-zeng/grpc,Vizerai/grpc,soltanmm/grpc,firebase/grpc,PeterFaiman/ruby-grpc-minimal,arkmaxim/grpc,jboeuf/grpc,grani/grpc,pszemus/grpc,ncteisen/grpc,msmania/grpc,dklempner/grpc,baylabs/grpc,yang-g/grpc,donnadionne/grpc,thinkerou/grpc,baylabs/grpc,rjshade/grpc,jboeuf/grpc,dklempner/grpc,kskalski/grpc,chrisdunelm/grpc,jtattermusch/grpc,grpc/grpc,ncteisen/grpc,MakMukhi/grpc,hstefan/grpc,thinkerou/grpc,infinit/grpc,infinit/grpc,simonkuang/grpc,ejona86/grpc,kskalski/grpc,y-zeng/grpc,kpayson64/grpc,baylabs/grpc,7anner/grpc,goldenbull/grpc,vjpai/grpc,stanley-cheung/grpc,carl-mastrangelo/grpc,a11r/grpc,ipylypiv/grpc,donnadionne/grpc,jboeuf/grpc,nicolasnoble/grpc,wcevans/grpc,vjpai/grpc,makdharma/grpc,jcanizales/grpc,dgquintas/grpc,murgatroid99/grpc,sreecha/grpc,sreecha/grpc,baylabs/grpc,adelez/grpc,Vizerai/grpc,grpc/grpc,jtattermusch/grpc,thinkerou/grpc,dklempner/grpc,philcleveland/grpc,a-veitch/grpc,yongni/grpc,MakMukhi/grpc,deepaklukose/grpc,donnadionne/grpc,yugui/grpc,kriswuollett/grpc,matt-kwong/grpc,ejona86/grpc,grani/grpc,kriswuollett/grpc,hstefan/grpc,Crevil/grpc,msmania/grpc,daniel-j-born/grpc,pszemus/grpc,arkmaxim/grpc,zhimingxie/grpc,ncteisen/grpc,matt-kwong/grpc,firebase/grpc,grpc/grpc,zhimingxie/grpc,LuminateWireless/grpc,philcleveland/grpc,thinkerou/grpc,PeterFaiman/ruby-grpc-minimal,dgquintas/grpc,soltanmm-google/grpc,vjpai/grpc,mehrdada/grpc,chrisdunelm/grpc,simonkuang/grpc,Crevil/grpc,a11r/grpc,jcanizales/grpc,royalharsh/grpc,soltanmm/grpc,andrewpollock/grpc,rjshade/grpc,ncteisen/grpc,y-zeng/grpc,ctiller/grpc,grpc/grpc,kriswuollett/grpc,ipylypiv/grpc,deepaklukose/grpc,muxi/grpc,carl-mastrangelo/grpc,kriswuollett/grpc,msmania/grpc,andrewpollock/grpc,LuminateWireless/grpc,pmarks-net/grpc,adelez/grpc,geffzhang/grpc,arkmaxim/grpc,matt-kwong/grpc,carl-mastrangelo/grpc,apolcyn/grpc,tengyifei/grpc,quizlet/grpc,malexzx/grpc,Vizerai/grpc,dklempner/grpc,stanley-cheung/grpc,yongni/grpc,ppietrasa/grpc,y-zeng/grpc,vjpai/grpc,podsvirov/grpc,wcevans/grpc,podsvirov/grpc,Vizerai/grpc,leifurhauks/grpc,arkmaxim/grpc,baylabs/grpc,perumaalgoog/grpc,vjpai/grpc,firebase/grpc,soltanmm/grpc,rjshade/grpc,nicolasnoble/grpc,pmarks-net/grpc,firebase/grpc,royalharsh/grpc,stanley-cheung/grpc,msmania/grpc,Vizerai/grpc,mehrdada/grpc,pszemus/grpc,msmania/grpc,carl-mastrangelo/grpc,PeterFaiman/ruby-grpc-minimal,yugui/grpc,stanley-cheung/grpc,podsvirov/grpc,donnadionne/grpc,hstefan/grpc,leifurhauks/grpc,greasypizza/grpc,ejona86/grpc,muxi/grpc,sreecha/grpc,kriswuollett/grpc,y-zeng/grpc,ejona86/grpc,bogdandrutu/grpc,ejona86/grpc,royalharsh/grpc,ejona86/grpc,quizlet/grpc,a-veitch/grpc,chrisdunelm/grpc,muxi/grpc,chrisdunelm/grpc,grani/grpc,daniel-j-born/grpc,Crevil/grpc