[TASK] Made abstract ExceptionHandler class an interface.

- Updated documentation to reflect new changes.

src/Pecee/Handler/IExceptionHandler.php

@@ -0,0 +1,11 @@
+<?php
+namespace Pecee\Handler;
+
+use Pecee\Http\Request;
+use Pecee\SimpleRouter\RouterEntry;
+
+interface IExceptionHandler {
+
+	public function handleError(Request $request, RouterEntry $router = null, \Exception $error);
+
+}