chore(ts): Disable new Strict Null Checking mode

Which warns about possibly 'undefined' objects.

More:
- https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-0.html
- microsoft/TypeScript#10642
- https://basarat.gitbooks.io/typescript/docs/options/strictNullChecks.html

Author: roalcantara

tsconfig.json

@@ -9,7 +9,8 @@
     "sourceMap": false,
     "strict": true,
     "moduleResolution": "node",
-    "noImplicitAny": false
+    "noImplicitAny": false,
+    "strictNullChecks": false
   },
   "include": [
     "./**/**.ts"