Add support for autocompletion, as with kubectl

[krook]

Other tools based on the same Cobra CLI framework have autocompletion support. This might make wsk CLI more user friendly.

spf13/cobra#69
https://kubernetes.io/docs/tasks/tools/install-kubectl/#enabling-shell-autocompletion

[rabbah]

wsk sdk install bashauto for bash tab completion.

[krook]

Cool. Looks like I can close this one. Is there another issue open to improve the docs for bashauto?

[rabbah]

There isn't.