Rename hosts to echo example, remove justtcp example

examples/justtcp/README.md

-# libp2p 'just tcp' example
-
-## What this does
-This example starts up a libp2p swarm that listens for tcp connections behind a
-multistream muxer protocol of `/plaintext/1.0.0`. All connections made to it
-will be echoed back.
-
-## Building
-```
-$ go build
-```
-
-## Usage
-```
-$ ./justtcp
-```

examples/justtcp/main.go

-package main
-
-import (
-	"context"
-	"fmt"
-	"os"
-
-	"github.com/libp2p/go-libp2p-swarm"
-	tcpt "github.com/libp2p/go-tcp-transport"
-	ma "github.com/multiformats/go-multiaddr"
-)
-
-func fatal(i interface{}) {
-	fmt.Println(i)
-	os.Exit(1)
-}
-
-func main() {
-	laddr, err := ma.NewMultiaddr("/ip4/0.0.0.0/tcp/5555")
-	if err != nil {
-		fatal(err)
-	}
-
-	// create a new swarm with a dummy peer ID, no private key, and no stream muxer
-	s := swarm.NewBlankSwarm(context.Background(), "bob", nil, nil)
-
-	// Add a TCP transport to it
-	s.AddTransport(tcpt.NewTCPTransport())
-
-	// Add an address to start listening on
-	err = s.AddListenAddr(laddr)
-	if err != nil {
-		fatal(err)
-	}
-
-	// Set a handler for incoming connections
-	s.SetConnHandler(func(c *swarm.Conn) {
-		fmt.Println("Got a new connection!")
-		defer c.Close()
-		buf := make([]byte, 1024)
-		for {
-			n, err := c.RawConn().Read(buf)
-			if err != nil {
-				fmt.Println(err)
-				return
-			}
-			fmt.Printf("read: %q\n", string(buf[:n]))
-
-			_, err = c.RawConn().Write(buf[:n])
-			if err != nil {
-				fmt.Println(err)
-				return
-			}
-		}
-	})
-
-	// Wait forever
-	<-make(chan bool)
-}