cli: bump amber-dev dependency to 0.1.6.

Fixes e8725b0e. The wrong package.json was bumped there.
Not reverting, though, as it does not harm, either.

external/amber-cli/package.json

@@ -40,7 +40,7 @@
     "grunt-init-amber": "~0.12.0",
     "grunt-init": "~0.3.1",
     "bower": "~1.3.2",
-    "amber-dev": "~0.1.2",
+    "amber-dev": "~0.1.6",
     "grunt-cli": "~0.1.13"
   }
 }