bumped up 0.3.7

[fixes]
- fix fclose warnings
- fix coding styles
- close connection after having exception on socket
- add retry_socket options

[misc]
- update vagrant box and use librarian-chef to manage cookbook.
- add stress test script into examples/stress. this usefull for testing
- fix testcases

[deprecated]
- throw away package.xml. we recommend to use composer
Merge branch 'master' into develop