DefaultHTMLDisplayer#getTemplate shouldn't create path with special characters

Current implementation of getTemplate might lead to create path with characters not supported by the filesystem. The definition of the method says it can create path such as html_displayer/[type]/[mode].vm. But a type can be something like List<String>, and < character is not supported in Windows filesystem.

We should not allow getTemplate to create such path and replace automatically those unsupported characters.