The old generate_sample.sh is broken already as it refers to
non-existing openstack/common path.

Let's use oslo-config-generator as many other OpenStack projects do.

Also, where applicable, option descriptions are updated with the
corresponding kernel parameters to set those options durig pxe boot.

Change-Id: Id4a0df30ea573d52f3b359f357fe8f4a29751939

Updated file tox.ini allows to check code style in all ".sh" files
included in Ironic Python Agent. Checking can be invoked by calling either
"tox" or "tox -e pep8".

Change-Id: Ie76605737c7db10a064f2aebfda388372a4c0591
Closes-Bug: #1625215

Copied generate_sample.sh and with_venv.sh
scripts from openstack/ironic. Generated
sample config.

Change-Id: I1beab119499156c711d838a3a1ecc3316b655900