feat: forbid working with Xcode below 9

Currently iOS Applications cannot be build with Xcode versions below 9. So forbid using such versions and show information to user that Xcode must be updated.

Author: rosen-vladimirov

npm-shrinkwrap.json

@@ -55,7 +55,7 @@
     "minimatch": "3.0.2",
     "mkdirp": "0.5.1",
     "mute-stream": "0.0.5",
-    "nativescript-doctor": "1.4.0",
+    "nativescript-doctor": "1.5.0",
     "nativescript-preview-sdk": "0.2.11",
     "open": "0.0.5",
     "ora": "2.0.0",