Add initial implementation for the CloudSigma's server context
Add the server context datasource in the main flags
Add ExtractIPs method to the Datasource interface
Add tests and simplify the userdata crunching
Fetch byte arrays from the serial console

That allows me use native IP guessing
Put cepgo in the source tree and use it from there
Remove leftover ExtractIPs method in remoteFile
refactor: Rename the server context flag to cloudsigma-metadata
refactor: Add goserial in third party modules