Adds the option of selecting the underlying eventmachine threadpool size when run in threaded mode.
Merge pull request #173 from joeljackson/master

Add setting to configure EM threadpool size.
Update usage page.
Pipelining is no longer supported.

Specs have been removed.
Accept absolute URL in request.
Update changelog.
Do not stop the EventMachine's reactor when Thin was started
inside a running loop.

Eg.:

  EM.run
    server = Thin::Server.start(3000)
    # This will NOT call EM.stop because Thin was started inside a
    # running loop.
    server.stop
  end
Add changelog for fix #177.
HEAD request no longer return a message-body in the response.

Closes #179
Name next release 1.6.0, Greek Yogurt.
No longer use toupper to convert headers as it is locale dependent.
Enhance the logging subsystem.

This patch enhances the logging functionality in a few
ways, namely:

 0. Separate the request tracing from logging
 1. logging level is now user controllable
    a. user can specify custom logger, thereby controlling
       how+where (level+file) messages are logged to.
 2. tracing is individually controllable
    a.  user can specify custom trace logger, getting
        all the benefits as stated above.

This patch retains the old logging mechanism (via the
new log_<level> mechanism. The old mechanism, if used,
emits deprecation warnings to stderr.

Of course, logging unit tests have been changed to test
this new functionality.
Fix with_redirected_stdout spec helper deps.
Add CHANGELOG entry for logging changes.
Rewrite change logs to be more user oriented.
Add entry for 'headers upcasing' bug.
Log nil Rack body as an error.
Refactor signal handling to happen outside of trap context.

Signal handling is done at one second intervals using an EM timer.
Change threadpool_size option to threadpool-size.

Add change log entry.
Update site w/ bundler usage.