加入screenshot用到的exception

src/screenshot/ConfigException.php

+<?php
+/**
+ * Created by IntelliJ IDEA.
+ * User: rek
+ * Date: 2017/7/14
+ * Time: PM12:40
+ */
+
+namespace neoteched\rpc\screenshot;
+
+
+use Exception;
+
+class ConfigException extends Exception {
+    const INVALID_FORMAT = 1;
+    const INVALID_URL = 2;
+    const INVALID_WIDTH = 3;
+    const INVALID_HEIGHT = 4;
+}
\ No newline at end of file

src/screenshot/ScreenshotException.php

+<?php
+/**
+ * Created by IntelliJ IDEA.
+ * User: rek
+ * Date: 2017/7/14
+ * Time: PM12:42
+ */
+
+namespace neoteched\rpc\screenshot;
+
+
+use Exception;
+
+class ScreenshotException extends Exception {
+}
\ No newline at end of file