resultfilename.h: detect Linux operating systems
rapidjsontest: update StatHandler

Inherit from BaseReaderHandler<> to properly handle calls to
the new `Key` function after updating RapidJSON to a current
version (see miloyip/rapidjson#132, miloyip/rapidjson#134).
Merge pull request #2 from pah/master

Detect Linux OS, minor RapidJSON fix