Add socket timeout option for HTTP requests

[dantrim]

What

This MR adds timeout_sec option to methods that create a socket for performing HTTP requests.

The signatures for the updated methods are such that the default is timeout_sec = 0, which means "no timeout", so any existing code should see no differences.

Related Issues

• Socket Timeout #33

[orca-zhang]

Thanks to you contribution.

The feature is great.
But I think use the type unsigned instead of type const unsigned& could be better.

[dantrim]

Sounds good @orca-zhang. I've changed the time in the latest commits.