Merge pull request #14 from Chilledheart/fix_sed_osx

[build] prevent bad sed usage under osx
[build] detect darwin platform correctly
Merge pull request #16 from Chilledheart/patch-2

[build] detect darwin platform correctly
add clang-format support
[build] add cmake build system

 - fix permission in searpc-codegen
 - remove shared library version
 - test support
 - python support
[lib] fix searpc codegen issue