feat(config): set default host/port from env vars
feat(config): set default host/port from env vars

This make it simpler to use Karma on Cloud9.
gdi2290/karma,jan-molak/karma,astorije/karma,Sanjo/karma,adamnation/karma,bertrandgressier/karma,yandex-lego/karma,WickyNilliams/karma,KrekkieD/karma,lencioni/karma,OniOni/karma,adamnation/karma,chrisirhc/karma,KrekkieD/karma,Basemm/karma,marthinus-engelbrecht/karma,wesleycho/karma,jeffjewiss/karma,shirish87/karma,matti/karma,mprobst/karma,buley/karma,IsaacChapman/karma,youprofit/karma,jamestalmage/karma,timebackzhou/karma,pedrosnk/karma,r3mi/karma,skycocker/karma,rhlass/karma,bitwiseman/karma,Klaudit/karma,swayf/karma,vtsvang/karma,jjoos/karma,jacopotarantino/karma,clbond/karma,aiboy/karma,timebackzhou/karma,oyiptong/karma,rageshkrishna/karma,brianmhunt/karma,skycocker/karma,buley/karma,johnjbarton/karma,powerkid/karma,codedogfish/karma,drkibitz/karma,hitesh97/karma,clbond/karma,marcodejongh/karma,czchen/karma,IveWong/karma,hitesh97/karma,cironunes/karma,xiaoking/karma,Klaudit/karma,gdi2290/karma,patrickporto/karma,IveWong/karma,vojtajina/karma,kahwee/karma,swayf/karma,matti/karma,buley/karma,jamestalmage/karma,OniOni/karma,rageshkrishna/karma,clbond/karma,rageshkrishna/karma,youprofit/karma,chrisirhc/karma,clbond/karma,kahwee/karma,pmq20/karma,behzad88/karma,behzad88/karma,harme199497/karma,Sanjo/karma,gayancliyanage/karma,lgalfaso/karma,pmq20/karma,mprobst/karma,david-garcia-nete/karma,jamestalmage/karma,pmq20/karma,growlybear/karma,czchen/karma,Dignifiedquire/karma,johnjbarton/karma,pedrotcaraujo/karma,maksimr/karma,dmitriiabramov/karma,jjoos/karma,rgaskill/karma,pedrotcaraujo/karma,karma-runner/karma,dmitriiabramov/karma,IveWong/karma,bertrandgressier/karma,panrafal/karma,panrafal/karma,unional/karma,sylvain-hamel/karma,brianmhunt/karma,stevemao/karma,fivetanley/karma,Sanjo/karma,bitwiseman/karma,simudream/karma,ernsheong/karma,growlybear/karma,marthinus-engelbrecht/karma,stevemao/karma,codedogfish/karma,david-garcia-nete/karma,simudream/karma,nmalaguti/karma,shirish87/karma,jsdir/karma,unional/karma,xiaoking/karma,rgaskill/karma,simudream/karma,johnjbarton/karma,kahwee/karma,gayancliyanage/karma,patrickporto/karma,pedrotcaraujo/karma,jacopotarantino/karma,IsaacChapman/karma,timebackzhou/karma,Sanjo/karma,panrafal/karma,hitesh97/karma,yandex-lego/karma,ijobling/karma,astorije/karma,thomasboyt/karma,rgaskill/karma,maksimr/karma,jan-molak/karma,codedogfish/karma,harme199497/karma,WickyNilliams/karma,oyiptong/karma,behzad88/karma,eddiemonge/karma,Dignifiedquire/karma,shirish87/karma,chrisirhc/karma,rhlass/karma,amagee/karma,nmalaguti/karma,pedrosnk/karma,johnjbarton/karma,viruschidai/karma,growlybear/karma,unional/karma,simudream/karma,cironunes/karma,Dignifiedquire/karma,KrekkieD/karma,david-garcia-nete/karma,adamnation/karma,eddiemonge/karma,yandex-lego/karma,youprofit/karma,harme199497/karma,marthinus-engelbrecht/karma,vtsvang/karma,karma-runner/karma,aiboy/karma,IsaacChapman/karma,jjoos/karma,vtsvang/karma,codedogfish/karma,thomasboyt/karma,patrickporto/karma,buley/karma,karma-runner/karma,youprofit/karma,viruschidai/karma,r3mi/karma,wesleycho/karma,ijobling/karma,pedrotcaraujo/karma,astorije/karma,chrisirhc/karma,xiaoking/karma,aiboy/karma,powerkid/karma,powerkid/karma,harme199497/karma,powerkid/karma,jjoos/karma,jsdir/karma,igorlima/karma,lencioni/karma,igorlima/karma,jeffjewiss/karma,oyiptong/karma,dmitriiabramov/karma,SamuelMarks/karma,brianmhunt/karma,stevemao/karma,pmq20/karma,SamuelMarks/karma,IsaacChapman/karma,jamestalmage/karma,patrickporto/karma,jsdir/karma,Basemm/karma,tomkuk/karma,IveWong/karma,KrekkieD/karma,mprobst/karma,bitwiseman/karma,kahwee/karma,Klaudit/karma,timebackzhou/karma,tomkuk/karma,skycocker/karma,pedrosnk/karma,rhlass/karma,drkibitz/karma,marthinus-engelbrecht/karma,jeffjewiss/karma,tomkuk/karma,tomkuk/karma,nmalaguti/karma,wesleycho/karma,marcodejongh/karma,amagee/karma,SamuelMarks/karma,sylvain-hamel/karma,gayancliyanage/karma,Klaudit/karma,xiaoking/karma,hitesh97/karma,unional/karma,maksimr/karma,rhlass/karma,astorije/karma,brianmhunt/karma,sylvain-hamel/karma,aiboy/karma,vojtajina/karma,Dignifiedquire/karma,vtsvang/karma,gayancliyanage/karma,vojtajina/karma,skycocker/karma,karma-runner/karma,lgalfaso/karma,wesleycho/karma,ernsheong/karma,fivetanley/karma,oyiptong/karma,ijobling/karma,lencioni/karma,nmalaguti/karma,stevemao/karma,ernsheong/karma