Set GDAXFeeModel as default fee model for Crypto securities
Set GDAXFeeModel as default fee model for Crypto securities

This prevents getting always zero fees in backtesting when not calling SetBrokerageModel

Jay-Jay-D/LeanSTP,StefanoRaggi/Lean,jameschch/Lean,StefanoRaggi/Lean,QuantConnect/Lean,StefanoRaggi/Lean,kaffeebrauer/Lean,QuantConnect/Lean,AlexCatarino/Lean,Jay-Jay-D/LeanSTP,kaffeebrauer/Lean,AnshulYADAV007/Lean,Jay-Jay-D/LeanSTP,jameschch/Lean,AlexCatarino/Lean,QuantConnect/Lean,AnshulYADAV007/Lean,redmeros/Lean,StefanoRaggi/Lean,AlexCatarino/Lean,AnshulYADAV007/Lean,Jay-Jay-D/LeanSTP,AnshulYADAV007/Lean,jameschch/Lean,jameschch/Lean,JKarathiya/Lean,JKarathiya/Lean,Jay-Jay-D/LeanSTP,AlexCatarino/Lean,JKarathiya/Lean,redmeros/Lean,kaffeebrauer/Lean,StefanoRaggi/Lean,AnshulYADAV007/Lean,kaffeebrauer/Lean,kaffeebrauer/Lean,JKarathiya/Lean,QuantConnect/Lean,jameschch/Lean,redmeros/Lean,redmeros/Lean