Expand API with new Machine, Interface, and Tags interfaces

[seanhoughton]

This PR adds a bunch of functionality. I haven't spent any time adding unit tests for the new functions or learning how the unit testing framework is set up, but it would be great if you could take a look and offer any suggestions or critiques before I spend any time on that.

This PR also adds a go module setup.

[jujubot]

Can one of the admins verify this patch?

[jujubot]

Can one of the admins verify this patch?

[mitechie]

Thanks, we'll see if we can get a look across things.

!!build!!