Run xcpretty from Bundler

Author: Pedro Piñera

.travis.yml

@@ -9,7 +9,7 @@ matrix:
       osx_image: xcode9.4
       xcode_scheme: ReactiveTask
       script:
-        - set -o pipefail && xcodebuild -workspace "$TRAVIS_XCODE_WORKSPACE" -scheme "$TRAVIS_XCODE_SCHEME" test | xcpretty
+        - set -o pipefail && xcodebuild -workspace "$TRAVIS_XCODE_WORKSPACE" -scheme "$TRAVIS_XCODE_SCHEME" test | bundle exec xcpretty
       env: JOB=Xcode9.4
     - os: osx
       osx_image: xcode9.4