feature: 95th percentile in latency statistics
feature: 95th percentile in latency statistics

This commit adds stats showing the 95th percentile latency when using the latency statistics flag (-l) or output to json flag (-o j)
Output examples:
Latency Distribution
     50%    79.57ms
     75%    84.17ms
     90%   115.31ms
     95%   241.90ms
     99%   248.48ms

"percentiles":{"50":0.000000,"75":0.000000,"90":0.000000,"95":117.775379,"99":117.775379}
codesenberg/bombardier,codesenberg/bombardier