chore: add engine entries to package.json

Fix angular#2712
Close angular#2715

Author: filipesilva

package.json

@@ -30,7 +30,8 @@
     "url": "https://github.com/angular/angular-cli.git"
   },
   "engines": {
-    "node": ">= 4.1.0"
+    "node": ">= 4.1.0",
+    "npm": ">= 3.0.0"
   },
   "author": "Angular Authors",
   "contributors": [

packages/angular-cli/package.json

@@ -15,7 +15,8 @@
     "url": "https://github.com/angular/angular-cli.git"
   },
   "engines": {
-    "node": ">= 4.1.0"
+    "node": ">= 4.1.0",
+    "npm": ">= 3.0.0"
   },
   "author": "Angular Authors",
   "license": "MIT",

packages/ast-tools/package.json

@@ -19,6 +19,10 @@
     "url": "https://github.com/angular/angular-cli/issues"
   },
   "homepage": "https://github.com/angular/angular-cli",
+  "engines": {
+    "node": ">= 4.1.0",
+    "npm": ">= 3.0.0"
+  },
   "dependencies": {
     "@angular/tsc-wrapped": "^0.3.0",
     "rxjs": "5.0.0-beta.11",

packages/webpack/package.json

@@ -13,6 +13,10 @@
     "url": "https://github.com/angular/angular-cli/issues"
   },
   "homepage": "https://github.com/angular/angular-cli/tree/master/packages/webpack",
+  "engines": {
+    "node": ">= 4.1.0",
+    "npm": ">= 3.0.0"
+  },
   "dependencies": {
     "@angular-cli/ast-tools": "^1.0.0"
   },