fix Opencart gitignore

opencart.gitignore

-image/cache
-system/cache
-system/database
-system/engine
-system/logs
-system/library
-system/helper
-download/
 config.php
 admin/config.php
+
+!index.html
+
+download
+image/cache/*.jpg
+image/cache/data/*
+system/cache
+system/logs