tokio::runtime::Handle for 0.3

[tbraun96]

What is the equivalent for 0.3? I can't seem to find a cloneable Handle

[nickkuk]

I think it will be Arc<Runtime>. But shutdown should be elaborated.

[Darksonn]

We are changing the Runtime::block_on method to take &self rather than &mut self in v0.3 in #2720, which removes the need for Handle. Check out the issue for more information.