fix(test): make this a simple helper

Assume we have a fully working GOPATH. Use a simple helper to keep me lazy.
feat(dbus): create the ObjectPath function
feat(dbus): add subscribe method

Don't setup subscribe by default. Make it an optional thing.
feat(dbus/methods): Add GetUnitProperties

this is a really common operation so make it simple and not require that
the user bail out to creating full dbus object paths and handling
dbus.Variants.
Merge pull request #19 from philips/various-cleanups-from-coreinit

Various cleanups from coreinit