Fixes #25: 40kb limit on html files

The `livereloadSnippet` sets the `Content-Length` of a response on each call to `res.write`. Additional calls will overwrite the content length without considering previous calls. Also, data passed to `res.end` are not taken into consideration.

This modification overrides the default response `write`, `writeHeader`, and `end` methods and writes the concatenated contents of all `write` requests in the new `end` method.

I tried to find a less hostile way of accomplishing this without overriding the response methods, but couldn't find any. Suggestions welcome.