fix wrong escaping of backslash in class-names when updating cronjobs_run table; add missing validateFormField-method for type 'image' (needs to be present but image-validation is handled elsewhere

Signed-off-by: Michael Kaufmann <d00p@froxlor.org>

lib/Froxlor/Validate/Form/Data.php

@@ -265,4 +265,10 @@ class Data
 
 		return $returnvalue;
 	}
+
+	public static function validateFormFieldImage($fieldname, $fielddata, $newfieldvalue)
+	{
+		// validation is handled in \Froxlor\Settings\Store::storeSettingImage()
+		return true;
+	}
 }