feat: (BREAKING CHANGE) overhaul libp2p config and constructor

* docs: update chat example and add info to its readme
* docs: update echo example
* docs: update libp2p in browser example
* docs: update pubsub example
* docs: update peer and content routing examples
* docs: update discovery mechanisms example
* docs: update encrypted comms example
* docs: update protocol and stream muxing example
* feat: add config validation
* test: update CI configs, use only node 8

test/utils/bundle-nodejs.js

@@ -0,0 +1,88 @@
+'use strict'
+
+const TCP = require('libp2p-tcp')
+const MulticastDNS = require('libp2p-mdns')
+const WS = require('libp2p-websockets')
+const Bootstrap = require('libp2p-railing')
+const SPDY = require('libp2p-spdy')
+const KadDHT = require('libp2p-kad-dht')
+const MPLEX = require('libp2p-mplex')
+const SECIO = require('libp2p-secio')
+const defaultsDeep = require('@nodeutils/defaults-deep')
+const libp2p = require('../..')
+
+function mapMuxers (list) {
+  return list.map((pref) => {
+    if (typeof pref !== 'string') { return pref }
+    switch (pref.trim().toLowerCase()) {
+      case 'spdy': return SPDY
+      case 'mplex': return MPLEX
+      default:
+        throw new Error(pref + ' muxer not available')
+    }
+  })
+}
+
+function getMuxers (muxers) {
+  const muxerPrefs = process.env.LIBP2P_MUXER
+  if (muxerPrefs && !muxers) {
+    return mapMuxers(muxerPrefs.split(','))
+  } else if (muxers) {
+    return mapMuxers(muxers)
+  } else {
+    return [MPLEX, SPDY]
+  }
+}
+
+class Node extends libp2p {
+  constructor (_options) {
+    const defaults = {
+      modules: {
+        transport: [
+          TCP,
+          WS
+        ],
+        streamMuxer: getMuxers(_options.muxer),
+        connEncryption: [
+          SECIO
+        ],
+        peerDiscovery: [
+          MulticastDNS,
+          Bootstrap
+        ],
+        dht: KadDHT
+      },
+      config: {
+        peerDiscovery: {
+          mdns: {
+            interval: 10000,
+            enabled: false
+          },
+          bootstrap: {
+            interval: 10000,
+            enabled: false,
+            list: _options.bootstrapList
+          }
+        },
+        relay: {
+          enabled: false,
+          hop: {
+            enabled: false,
+            active: false
+          }
+        },
+        dht: {
+          kBucketSize: 20
+        },
+        EXPERIMENTAL: {
+          dht: false,
+          pubsub: false
+        }
+      }
+    }
+
+    super(defaultsDeep(_options, defaults))
+  }
+}
+
+module.exports = Node