Maintain plugin preferencies

A fullfilled feature [CB-7142](https://issues.apache.org/jira/browse/CB-7142)
Supports:
* Maintaining plugin installation URL in config feature list to be able to restore with `cordova restore plugins`
* Maintaining plugin preferences in config feature list. Otherwize the plugin like [this](https://github.com/EddyVerbruggen/LaunchMyApp-PhoneGap-Plugin) fail to restore or be added after `cordova platform add` command