The `connector` argument for `request` (#27)

This is needed if http is run over unix socket. May also be used for
various kinds of proxies and potentially different transports

The implementation is partial. It doesn't use connector for Session yet.
Merge pull request #29 from tailhook/connector

The `connector` argument for `request` (#27)
fix tests
catch connection errors
handle malformed set-cookie header #30
Fixed unclosed warning in README.rst
Merge pull request #31 from RobberPhex/master

Fixed unclosed warning in README.rst
fix keep-alive in examples
Merge branch 'master' of github.com:KeepSafe/aiohttp