Add drone cron exec cmd (#180)

drone/cron/cron.go

@@ -13,5 +13,6 @@ var Command = cli.Command{
 		cronDeleteCmd,
 		cronDisableCmd,
 		cronEnableCmd,
+		cronExecCmd,
 	},
 }

drone/cron/cron_exec.go

@@ -0,0 +1,35 @@
+package cron
+
+import (
+	"errors"
+
+	"github.com/drone/drone-cli/drone/internal"
+	"github.com/urfave/cli"
+)
+
+var cronExecCmd = cli.Command{
+	Name:      "exec",
+	Usage:     "trigger cron job",
+	ArgsUsage: "[repo/name] [cronjob]",
+	Action:    cronExec,
+}
+
+func cronExec(c *cli.Context) error {
+	slug := c.Args().First()
+	owner, name, err := internal.ParseRepo(slug)
+	if err != nil {
+		return err
+	}
+
+	client, err := internal.NewClient(c)
+	if err != nil {
+		return err
+	}
+
+	cron := c.Args().Get(1)
+	if cron == "" {
+		return errors.New("missing cronjob name")
+	}
+
+	return client.CronExec(owner, name, cron)
+}