Support Ctrl+C to cancel a running query in the Influx CLI

[jsternberg]

The Influx CLI does not allow you to use Ctrl+C to cancel a running query. We should catch the signal and close the connection on the client side.

This may require a change to the Go client API.

[ghost]

Hi, I've been working on this the last couple of days. I have arrived at a solution using the context package. There was a small change on the client code to add a function "QueryWithContext". The solution is working
(main changes can be seen on my fork: emluque@d353e41 )but I'm still writing some tests, the whole thing should be done by end of week. I will then issue a pull request, I just wanted to claim the issue, since my solution is almost done.