Better defaults for Server.

* Use the intstrumented thread pool to give visibility of Jetty thread
  usage.
* Disable sending of Date and Server headers.
* Allow the server some grace period when shutting down to give requests
  a chance to complete cleanly.
Minor tweaks to external handler defaults.

* Use the X-Forwarded-For header for the remote address.
* Reuse sockets
Wrap external handler with instrumentation.

Use the InstrumentedHandler wrapper to get more metrics for the external
handler.
Enable GZip of responses.

If a client asks for it, attempt to compress responses for common text
only filetypes. No User-Agents are excluded as all of them should
support gzip correctly.
On error, attempt to stop the server.

Stop the server as best we can on error and allow the error to bubble up
to the main method so it choose what to do.
Merge pull request #10 from deverton/better-server-defaults

Nicer defaults for server, connector, and handlers