If an extension section exists the xml data in this section
is validated against the RelaxNG schema which must be part
of the xmlcatalog for the used extension namespace. If the
data validates the method get_extension_xml_data can be used
to access the etree parse result for each of the extension
configurations
This commit includes a validation in Command.run and Command.call
in order to verify the existance of the command before running it.
It case it is not found in the specified environment it raises a
KiwiCommandNotFound Exception.
This commit adds the execution of a jing process if the validation
fails, that way the user has more information about what is
actually failing during the validation process. If jing command
is not found, it just produces an info message to warn the user
and kiwi finalizes as expected.
nose is no longer maintained, thus we have to move to another
testing system. This commit updates the tox setup and all tests
to use pytest instead of nose.
