invoke cleanup after floodtest
Fix for issues/1

For a great range and small stepsize, generation of allowed messages introduced a bug.
The Time.now.to_i was executed in Rack::SimpleAuth#message where the current time +- delay was built to a proper hmac message.

For a great range and small stepsize this generation needed a specific time and sometimes longer than 1 second,
therefore Time.now.to_i has changed dynamically. This should be banned with following bugfix:

Set current time in rack middleware initializer and freeze (to prevent runtime change).