Added script to download SD files

.travis.yml

@@ -48,6 +48,8 @@ before_script:
 
   # For teensy build
   - sudo apt-get install realpath
+  # For nrf builds
+  - sudo ports/nrf/drivers/bluetooth/download_ble_stack.sh
   # For coverage testing (upgrade is used to get latest urllib3 version)
   - sudo pip install --upgrade cpp-coveralls
   - gcc --version