CLI cleanup (#33)

* Moved cli root command to tap subcommand.

* tap subcommand works.

* Added view and fetch placeholders.

* Updated descriptions.

* Fixed indentation.

* Added versio subcommand.

* Removed version flag.

* gofmt.

* Changed pod from flag to arg.

* Commented out "all namespaces" flag.

cli/cmd/version.go

@@ -0,0 +1,22 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+var Version = "0.1.0"
+
+var versionCmd = &cobra.Command{
+	Use:   "version",
+	Short: "Print version info",
+	RunE: func(cmd *cobra.Command, args []string) error {
+		fmt.Printf("mizu version %s\n", Version)
+		return nil
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(versionCmd)
+}