Add unit tests

[oliv3r]

To ensure future stability of this container, start adding some unit tests.

Since this is a mainly docker focused product, try to stick with docker supplied infra; https://docs.docker.com/docker-hub/builds/automated-testing/

[ozbillwang]

And something like this: https://github.com/sstephenson/bats ?

[oliv3r]

Yeah, I've used bats and it's quite nice; but I've since discovered https://github.com/kward/shunit2 which I found to be even nicer/more feature full.

[ozbillwang]

stale issue, no update, closed

[oliv3r]

@ozbillwang i don't think the issue is stale; i think this issue exists to track #10 ...

[ozbillwang]

ok, let's not work on that hard.

the unit test is for git funcitons and feature. But in our case, we just install it directly.