making the name lowercase in the addDetector method so that it will be found in the is() method fixes #2622 with tests.

lib/Cake/Network/CakeRequest.php

@@ -516,6 +516,7 @@ class CakeRequest implements ArrayAccess {
  * @return void
  */
 	public function addDetector($name, $options) {
+		$name = strtolower($name);
 		if (isset($this->_detectors[$name]) && isset($options['options'])) {
 			$options = Set::merge($this->_detectors[$name], $options);
 		}

lib/Cake/Test/Case/Network/CakeRequestTest.php

@@ -793,6 +793,11 @@ class CakeRequestTest extends CakeTestCase {
 
 		$_SERVER['TEST_VAR'] = 'wrong';
 		$this->assertFalse($request->is('compare'), 'Value mis-match failed.');
+		
+		$request->addDetector('compareCamelCase', array('env' => 'TEST_VAR', 'value' => 'foo'));
+
+		$_SERVER['TEST_VAR'] = 'foo';
+		$this->assertTrue($request->is('compareCamelCase'), 'Value match failed.');
 
 		$request->addDetector('banana', array('env' => 'TEST_VAR', 'pattern' => '/^ban.*$/'));
 		$_SERVER['TEST_VAR'] = 'banana';