Fix getLocalhostExternalIp

- api.externalip.net/ip no longer works; switching to ipecho.net/plain
Merge pull request #1224 from ahgittin/misc

misc improvements from the field: location API and better location data, minor other fixes
reinstate `installTo` method variant taking a `ResourceLoader` on `SshMachineLocation`
fail fast if os-details.sh is not on the classpath (eg if IDE hasn't compiled correctly with resources)