swift: log_statsd_sample_rate_factor = 0.01

make 'log_statsd_sample_rate_factor' configurable via puppet by making it a
parameter of swift::proxy, then set it to 0.01. it is drowning out everything
else on tungsten and makes it hard for me to debug things.

Change-Id: I00fc8e8cf204793a6d61376f752223a00b92170d