Merge pull request #23 from def/master

[linux] fill SwapMemoryStat.Sin/Sout from /proc/vmstat
fix error getting CPUInfo on darwin.
readLinesOffsetN helper for reading only specific part of the file
CPUTimes percpu for Linux
CPUTimes percpu for FreeBSD
CPUTimes percpu for Darwin
TODO: CPUTimes percpu for Windows
CPUPercent
Merge pull request #25 from KenjiTakahashi/cpu_percent

CPUTimes per cpu and CPUPercent
add a import.
value check to avoid zero division error.
use 10microsend duration for CPUPercent test.
Update README.rst

Corrected some typos and grammer errors.
Tweaked a couple of small things for consistency (section title capitalization, etc.).
Corrected a misreference to an added function CPUInfo (the function returned a CPUInfoStat struct, but the actual function name is CPUInfo).
Merge pull request #26 from logavanc/master

Update README.rst
Update README.rst

Corrected spelling error.
Merge pull request #27 from logavanc/master

Update README.rst
[linux] fix /proc/net/dev parsing