fix(2/init) message displayed during init

TODO use a writer to get the command output

resulting appearance:
```
go-ipfs (feat/machine-readable-logging) λ. make install_2; ipfs2 init -f
cd cmd/ipfs2 && go install
initializing ipfs node at /Users/btc/.go-ipfs
generating key pair...
peer identity: %s QmcPLgrqfvnneJ3vr3oGpkTiS9Psx8p3HxevjnoZYToDRm
```

License: MIT
Signed-off-by: Brian Tiger Chow <brian@perfmode.com>

cmd/ipfs2/init.go

@@ -209,7 +209,7 @@ func identityConfig(nbits int) (config.Identity, error) {
 		return ident, errors.New("Bitsize less than 1024 is considered unsafe.")
 	}
 
-	fmt.Printf("generating key pair...")
+	fmt.Println("generating key pair...")
 	sk, pk, err := ci.GenerateKeyPair(ci.RSA, nbits)
 	if err != nil {
 		return ident, err
@@ -228,7 +228,7 @@ func identityConfig(nbits int) (config.Identity, error) {
 		return ident, err
 	}
 	ident.PeerID = id.Pretty()
-	fmt.Println("generating key pair...")
+	fmt.Println("peer identity: %s", id.Pretty())
 
 	return ident, nil
 }