Fix the notification-id arg for the form notification update command

[richardW8k]

Supersedes #20 and #24

Fixes a notice which occurs when using the command without including the <notification-id> arg.

[18-Nov-2019 10:50:42 UTC] PHP Notice:  Undefined offset: 1 in /app/public/wp-content/plugins/gravityformscli/includes/class-gf-cli-form-notification.php on line 406
[18-Nov-2019 10:50:42 UTC] PHP Stack trace:
[18-Nov-2019 10:50:42 UTC] PHP   1. {main}() /usr/local/bin/wp:0
[18-Nov-2019 10:50:42 UTC] PHP   2. include() /usr/local/bin/wp:4
[18-Nov-2019 10:50:42 UTC] PHP   3. include() phar:///usr/local/bin/wp/php/boot-phar.php:11
[18-Nov-2019 10:50:42 UTC] PHP   4. WP_CLI\bootstrap() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/wp-cli.php:27
[18-Nov-2019 10:50:42 UTC] PHP   5. WP_CLI\Bootstrap\LaunchRunner->process() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/bootstrap.php:74
[18-Nov-2019 10:50:42 UTC] PHP   6. WP_CLI\Runner->start() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Bootstrap/LaunchRunner.php:23
[18-Nov-2019 10:50:42 UTC] PHP   7. WP_CLI\Runner->run_command_and_exit() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php:1132
[18-Nov-2019 10:50:42 UTC] PHP   8. WP_CLI\Runner->run_command() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php:394
[18-Nov-2019 10:50:42 UTC] PHP   9. WP_CLI\Dispatcher\Subcommand->invoke() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php:371
[18-Nov-2019 10:50:42 UTC] PHP  10. call_user_func:{phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/Subcommand.php:451}() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/Subcommand.php:451
[18-Nov-2019 10:50:42 UTC] PHP  11. WP_CLI\Dispatcher\CommandFactory::WP_CLI\Dispatcher\{closure:phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/CommandFactory.php:95-102}() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/Subcommand.php:451
[18-Nov-2019 10:50:42 UTC] PHP  12. call_user_func:{phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/CommandFactory.php:98}() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/CommandFactory.php:98
[18-Nov-2019 10:50:42 UTC] PHP  13. GF_CLI_Form_Notification->update() phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Dispatcher/CommandFactory.php:98

Testing Instructions

• Use the command without the <notification-id> arg e.g.
  wp gf form notification update 133 --notification-json='{"id":"5bacece91e2c9","to":"{admin_email}","name":"Admin Notification","event":"form_submission","toType":"email","subject":"New submission from {form_title}","message":"{all_fields}","isActive":false}'
• Find Error: Notification not found is returned and the notice is recorded in the sites debug.log file
• Switch to this branch
• Repeat command and find Success: Notification updated successfully is returned
• Use the command with the <notification-id> arg e.g. wp gf form notification update 133 5bacece91e2c9 --notification-json='{"to":"{admin_email}","name":"Admin Notification","event":"form_submission","toType":"email","subject":"New submission from {form_title}","message":"{all_fields}","isActive":true}'
• Find Success: Notification updated successfully is returned
• Use the command without the <notification-id> arg and without passing the notification id in the json e.g. wp gf form notification update 133 --notification-json='{"to":"{admin_email}","name":"Admin Notification","event":"form_submission","toType":"email","subject":"New submission from {form_title}","message":"{all_fields}","isActive":false}'
• Find Error: Please specify the ID of the notification to be updated is returned