Dealing with "null" encoding in RenderStream

[guillaumeprevot]

First of all, thank you for this great framework.

I found what looks like a bug in the org.debux.webmotion.server.render.RenderStream class (near line 76) :

if (encoding == null) {
    response.setCharacterEncoding(encoding);
} else {
    response.setCharacterEncoding(DEFAULT_ENCODING);
}

The code will use "encoding" if it's null instead of "DEFAULT_ENCODING".