In many times we would like to be able to import a single configuration from an Xml dump.

This feature would be useful to:
* Revert an undesired configuration deletion
* Synchronize configurations between servers that cannot communicate through the network

Please add the possibility to import a single configuration. The feature can be designed like this:
* In administration panel > Import > Configuration Export/Import > Configuration Import, add an Source configuration option
* This Source configuration will be optional to keep all actual features, or filled with the root configuration node by default
* Add a check box "recursively" to set if we want to import a single configuration or all the tree