Added completion for Homesick

Added completion for [Homesick](https://github.com/technicalpickles/homesick). Originally from https://github.com/liborw/homesick-completion.

[Homesick](https://github.com/technicalpickles/homesick) v1.0 was released earlier today - this PR also includes completion support for the new commands:

* cd
* destroy
* open
* version