Merge pull request #14 from def/master

change NumCtxSwitchesStat fields to int64
error handling in linux is now unsuppressed.

However, so many err check is introduced. Some refactoring is needed.
remove mustParse on frebsd.
refactoring.
fix darwin mem_swap parse error.
fix getPagesize parse error.
fix darwin netstat format parsing error.
remove "mustParse" function on darwin.
fix error handling.
Merge pull request #16 from shirou/errorhandling

Errorhandling
fix cpu info outofrange error on darwin.
add SerialNumber to DiskIOCounterStat.
sorry, I committed an old file.
Fix typo
Merge pull request #17 from slank/CPUPpercent-typo

Fix typo