Fix spelling error.
Refactor response methods in ProxyConnection

- Make response methods private.
- Rename #stub_request to #respond_from_stub
- Refactor actual response code to new #send_response method.
Update http_parser to 0.6.0 and remove CONNECT request hack
add travis-ci config
Merge pull request #37 from centro/refactor_proxy_response

Refactor proxy response
Merge pull request #38 from centro/update_http_parser

Update http_parser to 0.6.0 and remove CONNECT request hack
Fixes an issue where SSL requests can produce an invalid URL