use node-version-matches module.. add node 10 to travis

bin/cli.js

@@ -1,14 +1,7 @@
 #!/usr/bin/env node
-function validNodeVersion () {
-  var valid = false
-  try {
-    const semver = require('semver')
-    valid = semver.gte(require('process').version, '7.6.0')
-  } catch (err) {}
-  return valid
-}
+const nodeVersionMatches = require('node-version-matches')
 
-if (validNodeVersion()) {
+if (nodeVersionMatches('>=7.6.0')) {
   require('../lib/cli-app').run()
 } else {
   console.log('Sorry, this app requires node v7.6.0 or above. Please upgrade https://nodejs.org/en/')