Remove meters

Meters are a performance problem. They spam redis with zadd calls. This
creates undo memory growth in redis. Any backend worth their salt can
derive the rate by looking at the gauge readings sent in that interval.
This also makes counters long lived. You should not need to reset
counters anymore (unless you specifically want too). The functionality
was added to combat the memory growth of storing all the counters for a
potential meter reading
BREAKING! Bump version