This patch enables configfile autogeneration. It is triggered
* implicitly on every sphinx build
output dir: doc/source/html/_static/nova_dpm.conf.sample
for doc inclusion
* explicilty by tox -egenconfig
output dir: etc/nova/nova_dpm.conf.sample
* explicitly by tox -edocs
output dir: etc/nova/nova_dpm.conf.sample
In addition the return type of nova_dpm.conf.dpm.list_opts needed
to be changed to the default format (list of tuples).
Change-Id: Ib298b274f877d651dd846cac6525789c458da407
Closes-Bug: #1657701
8f82f0a442