This upgrade

- fixes Nxdtest to show proper traceback on error in configuration file

  nexedi/nxdtest@7b5add47

- adds preliminary support for PyLint[2]

  nexedi/nxdtest@72e36088

- and makes nxdtest to emit summary at the end of test run

  nexedi/nxdtest@9f413221

/reviewed-by @jerome
/reviewed-on nexedi/slapos!1081