`init` command in Go.

Open questions

 * How to do the config checking? Do we want to parse the config files in init
 and check for proper values? Or do we want to just check if the files exists
 and yell at user if the config is missing when they invoke a command that uses
 that config?

Change-Id: 5ab51c5e33
Story-Id: 79247470
Well, the main point was that I use `log.Ok` when an async task returns, i.e. a task shown to the user using `log.Go`. But yeah, this is open to discussion, but that is the convention now, so we should try to keep it consistent. Run other subcommands to see how the output usually looks like...