adjust saucelab grunt task to use env variable for username when available
adjust saucelab grunt task to use env variable for username when available

GabrielApG/FueLux-Elements,kinghigh/bootstrap,chriscorwin/fuelux,cormacmccarthy/fuelux,wakermahmud/fuelux,cormacmccarthy/fuelux,marcostomazini/fuelux,tweettypography/fuelux,fdumpling/fuelux,ASlave2Audio/fuelux,jasondavis/fuelux,tweettypography/fuelux,vernak2539/fuelux,itstar4tech/fuelux,jasondavis/fuelux,Jchavez/fuelux,swilliamset/fuelux,glizer/fuelux,oglandx/fuelux,ExactTarget/fuelux,oglandx/fuelux,imshibaji/fuelux,glizer/fuelux,futuremint/fuelux,dram1008/fuelux,dwaltz/fuelux,wakermahmud/fuelux,GabrielApG/FueLux-Elements,dram1008/fuelux,stevewithington/fuelux,fdumpling/fuelux,johan--/fuelux,interactivellama/fuelux,swilliamset/fuelux,marcostomazini/fuelux,Jchavez/fuelux,wakermahmud/fuelux,simonfork/fuelux,imshibaji/fuelux,futuremint/fuelux,rbmoore/fuelux,johan--/fuelux,afz/fuelux,rbmoore/fuelux,erpframework/fuelux,ExactTarget/fuelux,afz/fuelux,itstar4tech/fuelux,erpframework/fuelux,chriscorwin/fuelux,ASlave2Audio/fuelux,stevewithington/fuelux,simonfork/fuelux,BenjaminNeilDavis/fuelux,simonfork/fuelux,BenjaminNeilDavis/fuelux,erpframework/fuelux,dwaltz/fuelux,vernak2539/fuelux