Handle http(s) request errors

Add a handler for the 'error' event on the request object.
It sets a `error` field on the parser object and calls `after_parse`
with `success = false`
Discard response data when acting on headers alone.
Merge pull request #9 from bsander/feature/close-connections

Always consume response data in order for connection to close.
fixed tests
0.9.1
Merge pull request #8 from kunev/handle_request_errors

Handle http(s) request errors
0.9.2