Revert "kurento-module-scaffold: Add Gruntfile.js to module generation"

We are removing Grutfile.js from here and adding it to kurento-module-creator

This reverts commit 16af3cf20ee8391e80ac5b654f1db00d50834f9d.

Change-Id: If2e43f7fb18286d0b567c5f6d28dcf2870cb9765