Allow plus signs in URL's to pass unscathed in Helper functions.

According to  RFC 1738 the plus sign does not have special meaning outisde of the query part of a URL.

lib/Cake/Test/Case/View/HelperTest.php

@@ -660,6 +660,9 @@ public function testAssetUrl() {
 
 		$result = $this->Helper->assetUrl('foo.jpg?one=two&three=four');
 		$this->assertEquals('foo.jpg?one=two&three=four', $result);
+
+		$result = $this->Helper->assetUrl('dir/big+tall/image', array('ext' => '.jpg'));
+		$this->assertEquals('dir/big%2Btall/image.jpg', $result);
 	}
 
 /**
@@ -674,7 +677,8 @@ public function testAssetUrlNoRewrite() {
 			'here' => '/cake_dev/index.php/tasks',
 		));
 		$result = $this->Helper->assetUrl('img/cake.icon.png', array('fullBase' => true));
-		$this->assertEquals('http://localhost/cake_dev/app/webroot/img/cake.icon.png', $result);
+
+		$this->assertEquals($result, 'http://' . $_SERVER['HTTP_HOST'] . '/cake_dev/app/webroot/img/cake.icon.png');
 	}
 
 /**

lib/Cake/View/Helper.php

@@ -341,7 +341,7 @@ public function assetUrl($path, $options = array()) {
  */
 	protected function _encodeUrl($url) {
 		$path = parse_url($url, PHP_URL_PATH);
-		$parts = array_map('urldecode', explode('/', $path));
+		$parts = array_map('rawurldecode', explode('/', $path));
 		$parts = array_map('rawurlencode', $parts);
 		$encoded = implode('/', $parts);
 		return h(str_replace($path, $encoded, $url));