Don't just break for older nodes

bin/now.js

@@ -6,9 +6,16 @@ import {resolve} from 'path'
 // Packages
 import minimist from 'minimist'
 import {spawn} from 'cross-spawn'
+import nodeVersion from 'node-version'
 
 // Ours
 import checkUpdate from '../lib/check-update'
+import {error} from '../lib/error'
+
+if (nodeVersion.major < 6) {
+  error('Now requires at least version 6 of Node. Please upgrade!')
+  process.exit(1)
+}
 
 const argv = minimist(process.argv.slice(2))
 

package.json

@@ -86,6 +86,7 @@
     "minimist": "1.2.0",
     "ms": "0.7.2",
     "node-fetch": "1.6.3",
+    "node-version": "1.0.0",
     "progress": "1.1.8",
     "resumer": "0.0.0",
     "semver-compare": "1.0.0",