fix(@angular/cli): use quiet flag only in case of npm

Author: sumitarora

packages/@angular/cli/tasks/npm-install.ts

@@ -13,9 +13,9 @@ export default Task.extend({
 
     return new Promise(function(resolve, reject) {
       ui.writeLine(chalk.green(`Installing packages for tooling via ${packageManager}.`));
-      let installCommand = `${packageManager} --quiet install`;
-      if (packageManager === 'yarn') {
-        installCommand = `${packageManager} install`;
+      let installCommand = `${packageManager} install`;
+      if (packageManager === 'npm') {
+        installCommand = `${packageManager} --quiet install`;
       }
       exec(installCommand,
         (err: NodeJS.ErrnoException, _stdout: string, stderr: string) => {