chore: pin tns-core-modules devDep to next (NativeScript#873)

Author: Vasil Chimev

nativescript-angular/package.json

@@ -66,7 +66,7 @@
     "@angular/router": "~4.0.0 || ~4.1.0",
     "codelyzer": "^3.0.1",
     "rxjs": "^5.0.1",
-    "tns-core-modules": "^3.1.0",
+    "tns-core-modules": "next",
     "tslint": "^5.1.0",
     "typescript": "~2.3.2",
     "zone.js": "^0.8.4"