3.0.0

A bunch of things that have bugged me
 * Update everything to rojoma-json 3 / simple-arm 2
 * Requests now get a ResourceScope attached to prevent IoC hell when streaming responses
 * The logging MDC is automatically cleared around each request
 * Rework charset handling for text data everywhere.  It is now more flexible and harder to get wrong.
 * JSON responses have a convenience response builder for anything with an associated JsonEncode
 * There is a convenient class (HttpRequest) to hang app-specific request data off of.
 * Allow hooking into Jetty's error handling for custom error page formatting

not sure if officially this is supposed to be treated as None or as "" ?