Added better header parsing to Request-class.

- Added `tryParse` argument to the `getHeader` method. When enabled the method will try to parse headers from both server and client-side (enabled by default).
- Simplified references that checks for both variants of header (http/non http).
- Simplified getIp method of the Request-class.

src/Pecee/SimpleRouter/Router.php

@@ -305,8 +305,8 @@ class Router
      * Start the routing
      *
      * @return string|null
-     * @throws \Pecee\SimpleRouter\Exceptions\NotFoundHttpException
-     * @throws \Pecee\Http\Middleware\Exceptions\TokenMismatchException
+     * @throws NotFoundHttpException
+     * @throws TokenMismatchException
      * @throws HttpException
      * @throws \Exception
      */