added the ability to change the algorithm used to generate the token strings. added files missing in last commit

src/League/OAuth2/Server/Util/KeyAlgorithm/DefaultAlgorithm.php

@@ -0,0 +1,35 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: jderay
+ * Date: 3/11/14
+ * Time: 12:22 PM
+ */
+
+namespace League\OAuth2\Server\Util\KeyAlgorithm;
+
+
+class DefaultAlgorithm implements KeyAlgorithmInterface
+{
+    /**
+     * @param int $len
+     * @return string
+     * @throws \Exception
+     */
+    public function make($len = 40)
+    {
+        // We generate twice as many bytes here because we want to ensure we have
+        // enough after we base64 encode it to get the length we need because we
+        // take out the "/", "+", and "=" characters.
+        $bytes = openssl_random_pseudo_bytes($len * 2, $strong);
+
+        // We want to stop execution if the key fails because, well, that is bad.
+        if ($bytes === false || $strong === false) {
+            // @codeCoverageIgnoreStart
+            throw new \Exception('Error Generating Key');
+            // @codeCoverageIgnoreEnd
+        }
+
+        return substr(str_replace(array('/', '+', '='), '', base64_encode($bytes)), 0, $len);
+    }
+}

src/League/OAuth2/Server/Util/KeyAlgorithm/KeyAlgorithmInterface.php

@@ -0,0 +1,15 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: jderay
+ * Date: 3/11/14
+ * Time: 12:22 PM
+ */
+
+namespace League\OAuth2\Server\Util\KeyAlgorithm;
+
+
+interface KeyAlgorithmInterface
+{
+    public function make($len = 40);
+} 

tests/util/key_algorithm/DefaultAlgorithmTest.php

@@ -0,0 +1,24 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: jderay
+ * Date: 3/11/14
+ * Time: 12:31 PM
+ */
+
+use League\OAuth2\Server\Util\KeyAlgorithm\DefaultAlgorithm;
+
+class Default_Algorithm_test extends PHPUnit_Framework_TestCase
+{
+    public function test_make()
+    {
+        $algorithm = new League\OAuth2\Server\Util\KeyAlgorithm\DefaultAlgorithm();
+        $v1 = $algorithm->make();
+        $v2 = $algorithm->make();
+        $v3 = $algorithm->make(50);
+
+        $this->assertEquals(40, strlen($v1));
+        $this->assertTrue($v1 !== $v2);
+        $this->assertEquals(50, strlen($v3));
+    }
+}