Add parameter to set token bucket refill time, not just refill rate.

[evanmcneely]

The token bucket parameter refillRate is being used to set the bucket refill amount for every 1 second. Add a parameter refillFrequency to adjust to time between refills other than 1 second. Maybe it defaults to 1 second and maybe the parameter refillRate needs to be changed to refillAmount. The end goal is to be able to configure the algorithm to refill at a rate of 10 tokens a minute, for example.