chore(demos): add preinstall script

Refer `nativescript-dev-webpack` from a local `.tgz` file.

Author: vchimev

demo/AngularApp/package.json

@@ -30,7 +30,7 @@
   },
   "devDependencies": {
     "@ngtools/webpack": "6.1.0-rc.0",
-    "@angular/compiler-cli": "~6.1.0-beta.1",
+    "@angular/compiler-cli": "~6.1.0-beta.3",
     "@types/chai": "^4.0.2",
     "@types/mocha": "^2.2.41",
     "@types/node": "^7.0.5",
@@ -46,10 +46,11 @@
     "nativescript-dev-appium": "next",
     "nativescript-dev-sass": "next",
     "nativescript-dev-typescript": "next",
-    "nativescript-dev-webpack": "file:../..",
+    "nativescript-dev-webpack": "file:../../nativescript-dev-webpack.tgz",
     "typescript": "~2.7.2"
   },
   "scripts": {
+    "preinstall": "cd ../../ && npm install && npm pack && cp nativescript-dev-webpack*.tgz nativescript-dev-webpack.tgz",
     "e2e": "tsc -p e2e && mocha --opts ../config/mocha.opts --recursive e2e --appiumCapsLocation ../config/appium.capabilities.json",
     "compile-tests": "tsc -p e2e --watch"
   }

demo/JavaScriptApp/package.json

@@ -29,10 +29,11 @@
     "mocha-multi": "^0.11.0",
     "nativescript-dev-appium": "next",
     "nativescript-dev-sass": "next",
-    "nativescript-dev-webpack": "file:../..",
+    "nativescript-dev-webpack": "file:../../nativescript-dev-webpack.tgz",
     "node-sass": "^4.7.1"
   },
   "scripts": {
+    "preinstall": "cd ../../ && npm install && npm pack && cp nativescript-dev-webpack*.tgz nativescript-dev-webpack.tgz",
     "e2e": "mocha --opts ../config/mocha.opts --recursive e2e --appiumCapsLocation ../config/appium.capabilities.json"
   }
 }

demo/TypeScriptApp/package.json

@@ -30,10 +30,11 @@
     "nativescript-dev-appium": "next",
     "nativescript-dev-sass": "next",
     "nativescript-dev-typescript": "next",
-    "nativescript-dev-webpack": "file:../..",
+    "nativescript-dev-webpack": "file:../../nativescript-dev-webpack.tgz",
     "typescript": "~2.7.2"
   },
   "scripts": {
+    "preinstall": "cd ../../ && npm install && npm pack && cp nativescript-dev-webpack*.tgz nativescript-dev-webpack.tgz",
     "e2e": "tsc -p e2e && mocha --opts ../config/mocha.opts --recursive e2e --appiumCapsLocation ../config/appium.capabilities.json",
     "compile-tests": "tsc -p e2e --watch"
   }