Add tox.ini and few checker scripts

Add tox.ini and few checker scripts

(cherry-pick from master, also pasted current bash code style)

The plan is to change csit-validate-pylint-master job
to fail if (and only if) tox fails.

This will allow us to easily add checks,
with or without the voting power.

Each check produces log (ignored in .gitignore)
the voting job can archive.

+ Made autogen quiet by default, to avoid spam in autogen checker.
+ Unified the way direct csit subdirectories are git-ignored.

Change-Id: I6477b1ef7da6d3e30f68c5850d04900cc52f431e
Signed-off-by: Vratko Polak <vrpolak@cisco.com>