Log message:
Upgrade www/logswan to logswan-1.01

Upstream changelog
==================
Logswan 1.01 (2015-10-01)

- Documentation updates
- Fixing segfault when request data is empty or malformed (Thanks Jonathan
  Armani for reporting and proposing a fix)

Log message:
Import logswan-1.00 as www/logswan

Logswan is a fast Web log analyzer using probabilistic data structures. It is
targeted at very large log files, typically APIs logs. It has constant memory
usage regardless of the log file size, and takes approximatively 4MB of RAM.

Unique visitors counting is performed using two HyperLogLog counters (one for
IPv4, and another one for IPv6), providing a relative accuracy of 0.10%.

Project design goals include : speed, memory-usage efficiency, and keeping the
code as simple as possible.

Logswan is opinionated software :
 - It only supports the Common Log Format, in order to keep the parsing code
   simple
 - It does not split results per day, but log files can be split prior to being
   processed