fix(ts-helpers): support next minor pre release version of typescript

Closes #1

Author: Hotell

package.json

@@ -28,7 +28,7 @@
   "author": "Martin Hochel <hochelmartin@gmail.com>",
   "license": "MIT",
   "peerDependencies": {
-    "typescript": ">=1.8.0"
+    "typescript": ">=1.8.0 || >=1.9.0-dev"
   },
   "devDependencies": {
     "chai": "3.5.0",