Multiple workers, failing tests. :)
Passing (but lacking) specs after worker updates.
Limit worker queue to 1000 items
Move NullWorker.
Move init_workers
Auto-spawn worker
Auto-spawn agent
Include metrics count in debug log
Add Honeybadger.synchronize to synchronize with the agent.

This allows tests to make assertions on the test backend without
worrying about race conditions. Example:

  it "sends notifications to Honeybadger" do
    expect {
      Honeybadger.synchronize do
        50.times do
          Honeybadger.notify(StandardError.new('test backend'))
        end
      end
    }.to change(Honeybadger::Backend::Test.notifications[:notices], :size).by(50)
  end
Add Honeybadger.flush
Combine Agent#synchronize and Agent#flush
Just make #synchronize and #flush the same thing.

Hopefully this will avoid confusion.
Fix spelling and tweak comment.
Add examples for Honeybadger.flush
Fix example code
Add option to enable just debug logging...

...without changing the reporting interval.

The `debug` option sets an interval of 10 seconds *and* enables debug
logging. `logging.debug` enables *only* debug logging while leaving the
interval at 60 seconds.
Log flush events only when data is present.
Re-organizing agent/worker specs.
Add a todo
Test run when an exception occurs.