<?php
/**
 * Utility functions for the grid fields extension module.
 */
class GridFieldExtensions {

	public static function include_requirements() {
		$moduleDir = self::get_module_dir();
		Requirements::css($moduleDir.'/css/GridFieldExtensions.css');
		Requirements::javascript($moduleDir.'/javascript/GridFieldExtensions.js');
	}

	public static function get_module_dir() {
		return basename(dirname(__DIR__));
	}

}

<?php
/**
 * Utility functions for the grid fields extension module.
 */
class GridFieldExtensions {

	public static function include_requirements() {
		Requirements::css('gridfieldextensions/css/GridFieldExtensions.css');
		Requirements::javascript('gridfieldextensions/javascript/GridFieldExtensions.js');
	}

}

--- 
+++ 
@@ -5,8 +5,13 @@
 class GridFieldExtensions {
 
 	public static function include_requirements() {
-		Requirements::css('gridfieldextensions/css/GridFieldExtensions.css');
-		Requirements::javascript('gridfieldextensions/javascript/GridFieldExtensions.js');
+		$moduleDir = self::get_module_dir();
+		Requirements::css($moduleDir.'/css/GridFieldExtensions.css');
+		Requirements::javascript($moduleDir.'/javascript/GridFieldExtensions.js');
+	}
+
+	public static function get_module_dir() {
+		return basename(dirname(__DIR__));
 	}
 
 }
Fix - Support for module to be named other than "gridfieldextensions"
