Added missing engine parameter.

[bradcater]

Summary

This fixes the error "TypeError: set_keras_submodules() missing 1 required positional argument: 'engine'".

Related Issues

PR Overview

• [n] This PR requires new unit tests [y/n] (make sure tests are included)
• [n] This PR requires to update the documentation [y/n] (make sure the docs are up-to-date)
• [y] This PR is backwards compatible [y/n]
• [n] This PR changes the current API [y/n] (all API changes need to be approved by fchollet)

[fchollet]

You need to upgrade your version of keras_applications (sudo pip install keras_applications --upgrade).