fix(@angular/cli): save package on ng add

Before it was the job of the ng-add schematic to save the package. Now we do
it automatically. This is more expected (and works without ng-add schematics
if the user want to use "ng add moment" for example).

Author: hansl

packages/@angular/cli/commands/add.ts

@@ -67,7 +67,7 @@ export default class AddCommand extends SchematicCommand {
       this.logger,
       packageManager,
       this.project.root,
-      false);
+    );
 
     // Reparse the options with the new schematic accessible.
     options = await this._parseSchematicOptions(collectionName);

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

@@ -9,13 +9,13 @@ export type NpmInstall = (packageName: string,
                           logger: logging.Logger,
                           packageManager: string,
                           projectRoot: string,
-                          save: boolean) => void;
+                          save?: boolean) => void;
 
 export default async function (packageName: string,
                                logger: logging.Logger,
                                packageManager: string,
                                projectRoot: string,
-                               save: boolean) {
+                               save = true) {
   if (packageManager === 'default') {
     packageManager = 'npm';
   }