XmlParser: Improved XInclude Error Reporting

Due to the way XInclude is implemented in lxml, we are unable to get the
origin of each tag in the document. This patch provides our own
simplified implementation of XInclude resolving that fixes this problem.

Signed-off-by: Radek Pazdera <rpazdera@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
lnst-ctl: change meaning of -c option

This commit changes the meaning of the -c option. Previously this option
was used to perform config cleanup on machines before configuring them.
Since slaves are now capable of storing this configuration and perform
cleanup independently it is no longer needed.

The -c option is now used to specify an additional config file that
should be loaded after config files in standard places have been loaded.
This is a feature we agreed would be usefull for running automatic
tests.

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
NetTestSlave: cleanup when hello called

This commit moves the call of slave cleanup from the server loop to the
rpc method hello() as it makes more sense to do the cleanup whenever a
new session is started by the controller.

The rest of the patch changes related code on the controller side, this
is also related to the previous commit that removed the --cleanup option
and replaced it with --config.

Signed-off-by: Ondrej Lichtner <olichtne@redhat.com>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>