Refactor: LocationResolver accept any config

One can include any config in the spec, e.g. `byon(hosts="1.1.1.1",privateKeyFile="~/.ssh/mycustom.pem")`

This also adds support for locations specs in the form `byon(hosts="1.1.1.1")` as well as the old `byon:(hosts="1.1.1.1")` (note the colon is not needed).