Disable by default plugin installer

- There is no code review or any approval process to submit a plugin.
- Anyone can submit a backdoor as plugin.
- This is up to the Kanboard instance owner to validate if a plugin is legit.

config.default.php

@@ -24,8 +24,8 @@ define('PLUGINS_DIR', __DIR__.DIRECTORY_SEPARATOR.'plugins');
 // Plugins directory URL
 define('PLUGIN_API_URL', 'https://kanboard.org/plugins.json');
 
-// Enable/Disable plugin installer
-define('PLUGIN_INSTALLER', true);
+// Enable/Disable plugin installer (Disabled by default for security reason)
+define('PLUGIN_INSTALLER', false);
 
 // Available cache drivers are "file" and "memory"
 define('CACHE_DRIVER', 'memory');