Evaluate using wire for dependency injection

[philippgille]

I haven't worked with wire yet and on the first glance it doesn't look like it makes gokv easier than it already is (for example it looks like code generation is involved), but go-cloud uses wire and go-cloud is similar (at least in its goal to offer an abstraction layer to cloud storage) to gokv.

Also, GitHub user @gedw99 suggested using wire in #72.