Improvement/separate-core-and-extensions

Core and extensions features has been separated  in different features bundles. 

- Core feature: contains only bundles from OpenNaaS core (resources, security, persistence)

- Extensions features: every extension publishes its own feature catalog. For example, the router extension offers "opennaas-router" feature, containing the router repository, model, and capabilities.

- Drivers are defined in a different feature. For example, the router.driver.featuers contain features for Opener and 
Junos actionsets.

In order to provide an easier way to add all features to platform, another feature containing all extensions featuers has been created, colled org.opennaas.extensions.all.features, which has been added as a maven feature repository in platform.

This pull request needed to refactor all the test to call the new features. Also the SDNNetworkIntegrationTest has been adapted to pass, since we couldn't test it before due to "gave ups".