fallback to en_US locale if no pair for default currency
fallback to en_US locale if no pair for default currency

Closes #429

StephenBarnes/qtile,cortesi/qtile,nxnfufunezn/qtile,kopchik/qtile,dequis/qtile,flacjacket/qtile,nxnfufunezn/qtile,qtile/qtile,kynikos/qtile,rxcomm/qtile,qtile/qtile,de-vri-es/qtile,encukou/qtile,rxcomm/qtile,kopchik/qtile,andrewyoung1991/qtile,kiniou/qtile,kseistrup/qtile,w1ndy/qtile,himaaaatti/qtile,encukou/qtile,dequis/qtile,cortesi/qtile,kseistrup/qtile,zordsdavini/qtile,tych0/qtile,jdowner/qtile,w1ndy/qtile,apinsard/qtile,farebord/qtile,EndPointCorp/qtile,aniruddhkanojia/qtile,andrewyoung1991/qtile,kiniou/qtile,xplv/qtile,aniruddhkanojia/qtile,xplv/qtile,EndPointCorp/qtile,kynikos/qtile,zordsdavini/qtile,frostidaho/qtile,jdowner/qtile,de-vri-es/qtile,StephenBarnes/qtile,ramnes/qtile,tych0/qtile,flacjacket/qtile,soulchainer/qtile,apinsard/qtile,ramnes/qtile,farebord/qtile,frostidaho/qtile,himaaaatti/qtile,soulchainer/qtile