Generate the Neutron VPNaaS sample config files by using the oslo
generator. The files are generated with a .sample extension and
replace the static example configuration files.
Once the generation code is delivered, the static config files
will be removed.
Change-Id: Icef8f7e8f0e8e78bfffa7a5af3f9f2300376b115
Related-blueprint: autogen-neutron-conf-file
Partial-bug: #1199963
Depends-On: I4a6094b8218dfd320d05bfb1e3bc121e8930c551