Unit tests and I/O bindings (#8)

* Added composer config, added IO/error tests using phpunit

* Added ApiGen doc comments

* Added test to ensure last_error is not set from loading up the CRT

lib/tests/EventLoopGroupTest.php

@@ -0,0 +1,18 @@
+<?php
+
+require_once('tests.inc');
+
+final class EventLoopGroupTest extends PHPUnit_Framework_TestCase {
+
+    public function testLifetime() {
+        $elg = new EventLoopGroup(new EventLoopGroupOptions());
+        $elg = null;
+    }
+
+    public function testConstructionWithOptions() {
+        $options = new EventLoopGroupOptions();
+        $options->num_threads = 1;
+        $elg = new EventLoopGroup($options);
+        $elg = null;
+    }
+}