Missing column produces stack dump in pedsnet-etlprov

[murphyke]

The steps.csv file of one site was missing the last column, which caused the following output.

panic: runtime error: index out of range

goroutine 1 [running]:
main.(*Parser).parseStep(0xc820149f08, 0xc820192280, 0x4, 0x4, 0x0, 0x0, 0x0)
        /Users/ruthb/Code/go/src/github.com/PEDSnet/tools/cmd/etlprov/parser.go:174 +0x685
main.(*Parser).ReadSteps.func1(0xc820192280, 0x4, 0x4)
        /Users/ruthb/Code/go/src/github.com/PEDSnet/tools/cmd/etlprov/parser.go:408 +0x73
main.ReadRows(0x1160370, 0xc82002c100, 0xc820149908, 0x0, 0x0)
        /Users/ruthb/Code/go/src/github.com/PEDSnet/tools/cmd/etlprov/reader.go:79 +0x33d
main.(*Parser).ReadSteps(0xc820149f08, 0x1160370, 0xc82002c100, 0x0, 0x0, 0x0)
        /Users/ruthb/Code/go/src/github.com/PEDSnet/tools/cmd/etlprov/parser.go:424 +0xb8
main.(*Parser).ReadDir(0xc820149f08, 0x3ecec8, 0x1, 0xc820149d30, 0x0, 0x0)
        /Users/ruthb/Code/go/src/github.com/PEDSnet/tools/cmd/etlprov/parser.go:692 +0x346
main.main()
        /Users/ruthb/Code/go/src/github.com/PEDSnet/tools/cmd/etlprov/main.go:107 +0x10b6
...