Add Intentions Support

[hadrabap]

Hello,

I wanted to control Consul Intentions from a remote application and I found there is no support for connect at all. I've implemented it. Could you please take a look at it?

Thanks a lot.

The code is here: https://github.com/hadrabap/consul-api/tree/feature/issue-207-224

P.S.: The code implements #207 as well too.