func NewShellTaskT(transform goauto.Transformer, cmd string, args ...string) goauto.Tasker {
	return &shellTask{cmd: cmd, args: args, transform: transform}
}
NewShellTaskT returns a goauto.Tasker which calls out to the shell with the command cmd and arguments arg
the goauto.TaskInfo.Target will be the last argument and is generated by transform(goauto.TaskInfo.Src)
goauto.TaskInfo.Target is set to transform(goauto.TaskInfo.Src)
package shelltask
import (
	"fmt"
	"io"
	"os"
	"os/exec"
	"time"
	"github.com/dshills/goauto"
)
type shellTask struct {
	cmd       string
	args      []string
	transform goauto.Transformer
}
func NewShellTask(cmd string, args ...string) goauto.Tasker {
	return &shellTask{cmd: cmd, args: args, transform: goauto.Identity}
}