add version command

cmd/version.go

@@ -0,0 +1,26 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+// TODO: insert automatically via build step?
+const (
+	VERSION   = "1.0.7"
+	BUILDDATE = "2018-06-26T00:59:00+02"
+)
+
+func init() {
+	rootCmd.AddCommand(versionCmd)
+}
+
+var versionCmd = &cobra.Command{
+	Use:   "version",
+	Short: "Get build and version information",
+	Long:  "osem_notify version returns its build and version information",
+	Run: func(cmd *cobra.Command, args []string) {
+		fmt.Printf("%s %s", VERSION, BUILDDATE)
+	},
+}