Updates console to inform user of an ongoing package download.

Console message turns red after 1 second.

lib/versions/npm.js

@@ -1,6 +1,8 @@
-let fs = require('../core/fs.js');
-
-let PluginManager = require('live-plugin-manager').PluginManager;
+const fs = require('../core/fs.js');
+const {PerformanceObserver, performance} = require('perf_hooks');
+const PluginManager = require('live-plugin-manager').PluginManager;
+require('colors');
+const _ = require('underscore');
 
 class Npm {
 
@@ -17,9 +19,62 @@ class Npm {
       return callback(null, packageDirectory + packageName);
     }
 
-    this.logger.info("downloading " + packageName + " " + version + "....");
-    this.logger.info(__("downloading {{packageName}} {{version}}....", {packageName: packageName, version: version}));
+    this.logger.info(__("Downloading {{packageName}} {{version}}...", {packageName: packageName, version: version}));
+
+    const obsMeasure = new PerformanceObserver((items) => {
+      let entry;
+      let strDuration;
+
+      // find any download ongoing measurements we've made
+      entry = _.last(_.where(items.getEntries(), {name: downloadOngoing}));
+      if(entry){
+        // ongoing performance mark 
+        strDuration = __('Still downloading {{packageName}} {{version}}... ({{duration}}ms elapsed)', {packageName: packageName, version: version, duration: entry.duration});
+      }
+      else{
+        // otherwise, find our download complete measurement
+        entry = _.last(_.where(items.getEntries(), {name: downloadComplete}));
+        
+        if(entry){
+          strDuration = __('Finished downloading {{packageName}} {{version}} in {{duration}}ms', {packageName: packageName, version: version, duration: entry.duration});
+          performance.clearMarks();
+        }
+      }
+      
+      // log our measurement and make it red if it has taken too long
+      if(entry && strDuration){
+        if(entry.duration > 1000){
+          strDuration = strDuration.red;
+        }
+        this.logger.info(strDuration);
+      }
+      
+    });
+    obsMeasure.observe({entryTypes: ['measure']});
+
+    // define mark and measurement names
+    let startMark = 'downloadStart' + packageName + version;
+    let ongoingMark = 'downloadOngoingMark' + packageName + version;
+    let downloadOngoing = 'downloadOngoing' + packageName + version;
+    let endMark = 'downloadEnd' + packageName + version;
+    let downloadComplete = 'downloadComplete' + packageName + version;
+
+    // mark our start time
+    performance.mark(startMark);
+    
+    // function that continually updates the console to show user that we're downloading a library
+    let intOngoingDownload = setInterval(
+      function(){ 
+        performance.mark(ongoingMark);
+        performance.measure(downloadOngoing, startMark, ongoingMark); 
+      }, 750);
+
+    // do the package download/install
     manager.install(packageName, version).then((result) => {
+      // stop updating console for ongoing download
+      clearInterval(intOngoingDownload);
+      performance.mark(endMark);
+      performance.measure(downloadComplete, startMark, endMark);
       callback(null , result.location);
     }).catch(callback);
   }