Avoid double bundle install

Travis automatically calls this during the install phase.
See https://docs.travis-ci.com/user/customizing-the-build/ for more info

.travis.yml

@@ -35,7 +35,7 @@ matrix:
       env: DEVICE="iPad Pro" VERSION=9.1
 before_install:
   - export LANG=en_US.UTF-8
-  - bundle install
+before_script:
   - bundle exec pod install --project-directory=Demo
 script:
   - xctool -sdk iphonesimulator -workspace Demo/NUIDemo.xcworkspace -scheme NUITests -destination "platform=iOS Simulator,name=$DEVICE,OS=$VERSION" clean test