Initial import from Alltube app

Removed dependency on Config and LocaleManager classes
Avoid using generic exceptions

classes/exceptions/InvalidProtocolConversionException.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Alltube\Library\Exception;
+
+/**
+ * Invalid conversion.
+ */
+class InvalidProtocolConversionException extends AlltubeLibraryException
+{
+    /**
+     * InvalidProtocolConversionException constructor.
+     * @param string $protocol Protocol
+     */
+    public function __construct($protocol)
+    {
+        parent::__construct($protocol . ' protocol is not supported in conversions.');
+    }
+}