Configure the scope of the statsd histogram (fixes #401)

  - Our current statsd implementation will staticaly span a histogram of 1000 (HUGE!) entries in 1ms resolution
  - since this resolution isn't configurable percentile aggregation may only take into account values up to 1s
  - Make the resolution of our histogram configurable, so the user can decide on which resolution his values will be in
  - default the resolution to 20ms, so that by default we will be able to cope values up to 20s
  - if a value exceeds the span of our histogram, add it to our max histogram item instead of ignoring it - if the 'focus' of our histogramm is exceeded, this produces better values.

thanks @zarath for discussing this topic and review.