Switch from kingpin to cobra

This enables easier use of sub-commands for flexibility

cmd/helpers.go

@@ -0,0 +1,19 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+func usage_er(cmd *cobra.Command, msg interface{}) {
+	cmd.Usage()
+	fmt.Println("")
+	er(msg)
+}
+
+func er(msg interface{}) {
+	fmt.Println("ERROR:", msg)
+	os.Exit(1)
+}