fix: Persist style extension config at project creation.

Closes #780

Author: pkamdem

addon/ng2/blueprints/ng2/files/angular-cli.json

@@ -25,7 +25,7 @@
   "defaults": {
     "prefix": "<%= prefix %>",
     "sourceDir": "<%= sourceDir %>",
-    "styleExt": "css",
+    "styleExt": "<%= styleExt %>",
     "prefixInterfaces": false
   }
 }