after this ,user is able to explore the configurations of
nova zvm driver supported.
part of blueprint:zvm_doc_update
Change-Id: Id58b5a5d9ebb7a9304e150e4c0471046ff6b1620
Currently the configuration are in driver.py, but not automatically
generated during build phase.
This patch enables 'tox -egenconfig' to build a sample conf file
and put into etc/nova-zvm.conf.sample, so if we need, we can paste
those info into nova.conf.sample when we do further build.
Follow up patches need to adjust the words in driver.py so
the auto generated conf.sample will be more helpful to user.
Change-Id: Ic35ecc8331c03bfe22e3077a8387ddfc1c8fb3d0