Add lightynode support to testutils.py

Add lightynode support to testutils.py

- add netconf_client dependency necessary for several tests
- add an installation shell script for lighty_node
- use sed in lightynode and hondenynoe install scripts to deal
  with 1.2.1 sample configs typo issue
- add an environment variable to configure a choice
  among lighty / honeycomb / no simulator
- update tox.ini consequently

JIRA: TRNSPRTPCE-754
Signed-off-by: guillaume.lambert <guillaume.lambert@orange.com>
Co-authored-by: Christophe Betoule <christophe.betoule@orange.com>
Change-Id: I167b40dd3a1d9bd89cc472fa80899ba730f99c6a