Remove un-used resources (app example)
travis.yml: Store NOM_DEPS_URL env var in script

I've decided that it is probably best to place the download URL
inside our travis-ci script instead of fetching it from the
repository's settings, both for sake of transparency and for future
maintenance. The NOM_DEPS_URL var as a setting does not allow us to
preserve the build state relative to the dependencies used whereas
storing the var in the script does.
travis-ci: Re-enable tar verbosity

(Debugging missing librocket headers issue)