Added support for showing current k8s context

[marcjoha]

Shows the currently active Kubernetes context, pulled from ~/.kube/config. Similar to prompt customizations like https://github.com/jonmosco/kube-ps1.

I'm not very good with Node, and new to Hyper, so pretty sure I made some beginner's mistakes. Happy to pitch in more time to polish this if you're up for merging. In any case, thanks for an awesome plugin.

[j-f1]

I’m maintaining a fork so feel free to open a PR over there & I’ll try to review your changes and merge them in the fork, since @henrikdahl hasn’t merged anything recently.