Change. Try use existing log file after create file writer.
Fix. incorrect methods calls in `writer.file.roll`
Fix. Set current size/rows for reuse log only if needed.
Add. Some tests.
Add. Travis files.
Fix. Test works with LuaFileSystem 1.6.2 on *nix.
Merge pull request #5 from moteus/reuse_log_file

Reuse existing log file