Don't register actions when WooCommerce isn't active

Otherwise it will result in fatal errors like this:

```
[08-Mar-2017 15:03:35 UTC] PHP Fatal error:  Uncaught Error: Call to undefined function wc_get_order() in /srv/git/_wordpoints-modules/woocommerce/src/classes/hook/action/order/delete.php:23
Stack trace:
#0 /srv/git/wordpoints/src/classes/hook/router.php(147): WordPoints_WooCommerce_Hook_Action_Order_Delete->should_fire()
#1 /srv/git/wordpoints/src/classes/hook/router.php(94): WordPoints_Hook_Router->route_action('delete_post,10', Array)
#2 /srv/www/wordpress-develop/src/wp-includes/class-wp-hook.php(298): WordPoints_Hook_Router->__call('delete_post,10', Array)
#3 /srv/www/wordpress-develop/src/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters(NULL, Array)
#4 /srv/www/wordpress-develop/src/wp-includes/plugin.php(453): WP_Hook->do_action(Array)
#5 /srv/www/wordpress-develop/src/wp-includes/post.php(2508): do_action('delete_post', '143')
#6 /srv/www/wordpress-develop/src/wp-includes/post.php(6048): wp_delete_post('143', true)
#7 /srv/www/wordpress-develop/src/wp-includes/class-wp-hook.php(298): wp_delete_auto_drafts()
#8 /srv/www/wordpress-develo in /srv/git/_wordpoints-modules/woocommerce/src/classes/hook/action/order/delete.php on line 23
```

If WooCommerce isn't active, our events and actions won't operate properly, and neither will our entities, etc. So there is no since in registering them.

src/includes/actions.php

@@ -7,6 +7,11 @@
  * @since   1.1.0
  */
 
+// Don't hook up the actions if WooCommerce isn't active.
+if ( ! function_exists( 'wc_get_order' ) ) {
+	return;
+}
+
 add_action( 'wordpoints_init_app_registry-apps-entities', 'wordpoints_woocommerce_entities_init' );
 add_action( 'wordpoints_init_app_registry-entities-restrictions-know', 'wordpoints_woocommerce_entity_restrictions_know_init' );