Update .travis.yml
Update .travis.yml

Clone NDK from bugsnag repo
bugsnag/bugsnag-android-gradle-plugin,bugsnag/bugsnag-android-gradle-plugin,bugsnag/bugsnag-android-gradle-plugin,bugsnag/bugsnag-android-gradle-plugin,bugsnag/bugsnag-android-gradle-plugin,bugsnag/bugsnag-android-gradle-plugin