Chunked transfer encoding effectively disables browser caching

OpenCMIS never sets the Content-length on HTTP responses, letting the app server use the default strategy of sending them with a "Transfer-encoding: chunked" header.
While it's valid HTTP 1.1, it's not fully supported by e.g. some browsers and cache middleware, which handle such responses fine but fail to cache them.

Please provide to either set the content-length at least in the getContentStream calls, or allow users to hook into the HTTP serialization process.