Simplified Signal.concat implementation
Simplified Signal.concat implementation

ohwutup/ReactiveCocoa,paulyoung/ReactiveCocoa,paulyoung/ReactiveCocoa,smilypeda/ReactiveCocoa,andersio/ReactiveCocoa,rpowelll/ReactiveCocoa,natestedman/ReactiveCocoa,victorlin/ReactiveCocoa,tzongw/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,Farteen/ReactiveCocoa,tonyarnold/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,calebd/ReactiveCocoa,walkingsmarts/ReactiveCocoa,Juraldinio/ReactiveCocoa,ohwutup/ReactiveCocoa,victorlin/ReactiveCocoa,sandyway/ReactiveCocoa,smilypeda/ReactiveCocoa,Farteen/ReactiveCocoa,rpowelll/ReactiveCocoa,paulyoung/ReactiveCocoa,llb1119/test,kevin-zqw/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,Farteen/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,sandyway/ReactiveCocoa,kevin-zqw/ReactiveCocoa,ikesyo/ReactiveCocoa,natestedman/ReactiveCocoa,tonyarnold/ReactiveCocoa,calebd/ReactiveCocoa,walkingsmarts/ReactiveCocoa,ohwutup/ReactiveCocoa,victorlin/ReactiveCocoa,llb1119/test,llb1119/test,natestedman/ReactiveCocoa,calebd/ReactiveCocoa,yonekawa/ReactiveCocoa,smilypeda/ReactiveCocoa,rpowelll/ReactiveCocoa,Juraldinio/ReactiveCocoa,tonyarnold/ReactiveCocoa,sandyway/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,ikesyo/ReactiveCocoa,yonekawa/ReactiveCocoa,Juraldinio/ReactiveCocoa,tzongw/ReactiveCocoa,kevin-zqw/ReactiveCocoa,andersio/ReactiveCocoa,andersio/ReactiveCocoa,walkingsmarts/ReactiveCocoa,tzongw/ReactiveCocoa,yonekawa/ReactiveCocoa