fix: add node@10, remove node@4

This is a non-breaking change, and only shows a warning once a week:

[nodemon] WARNING: node@v4.8.7 is no longer maintained, nor supported by nodemon
More information: https://github.com/nodejs/Release#end-of-life-releases

.travis.yml

@@ -5,10 +5,10 @@ cache:
 notifications:
   email: false
 node_js:
+  - '10'
   - '9'
   - '8'
   - '6'
-  - '4'
 before_install:
   - if [ "$TRAVIS_PULL_REQUEST_BRANCH" == "" ]; then echo "//registry.npmjs.org/:_authToken=\${NPM_TOKEN}" >> .npmrc; fi
 after_success:

lib/nodemon.js

@@ -272,6 +272,28 @@ nodemon.reset = function (done) {
   bus.emit('reset', done);
 };
 
+bus.once('reset', () => {
+  // FIXME only once a week
+  if (utils.version.major < 6) {
+    const Configstore = require('configstore');
+    const pkg = require(__dirname + '/../package.json');
+    const now = Date.now();
+
+    const week = 1000 * 60 * 60 * 24 * 7;
+    const key = 'lastNodeWarning';
+
+    // create a Configstore instance with an unique ID e.g.
+    // Package name and optionally some default values
+    const conf = new Configstore(pkg.name);
+    const last = conf.get(key);
+
+    if (!last || now - week > last) {
+      utils.log.error(`WARNING: node@${process.version} is no longer maintained, nor supported by nodemon\nMore information: https://github.com/nodejs/Release#end-of-life-releases`);
+      conf.set(key, now);
+    }
+  }
+});
+
 bus.on('reset', function (done) {
   debug('reset');
   nodemon.removeAllListeners();