Add ability to add localconnector feature automatically to server.xml

For the managed container for Liberty to connect to a liberty instance, the localConnector-1.0 feature needs to be present in server.xml.

This is somewhat of an obstacle when using a CI managed Liberty, where a Liberty instance is downloaded and installed from Maven during the test. Following the work done in ARQ-1729 it should be relatively easy to add this localConnector-1.0 feature to server.xml.

I would like to propose adding a new boolean to the configuration for the managed Liberty container, and when set to true the Arquillian container will add the mentioned feature and will thus be able to start Liberty without requiring the user to modify the installation first.

(I'll look into doing a PR for this)