Add lock_configuration, unlock_configuration and load_configuration

[krihal]

Three new capabilities.

[fbouliane]

Hi Kihal,
Thanks for the pull-request !

As we are trying to have achieve as much coverage in unit test as possible, do you have sample on how a real switch reacts when you issue those commands (xml rpc payload). I guess you can take a look at the netconf_protocol_test.py to understand how we test things. We could add those payloads to explain how the switch reacts to those commands.

Also, after a quick look I'm not sure adding those methods resulted in any feature. Does this change the initial capability message ?

Thanks again

[fbouliane]

Would need more details as unit test or explanation of usage of the feature.
Thanks