provide API for admin user to show neutron configure

[yong sheng gong]

problem:
physical networks are defined in configure file of neutron, admin does not have way to show the system configure.
some upper apps need these information. for example horizon allows the admin to create a network for target project, but horizon cannot fill in the physical network select box with neutron supported physical networks, cannot fill in the supported network type supported in neutron either.

expectation:
provide API to get neutron server configuration, return the json.

[Victor Morales (electrocucaracha)]

Hey Yong I've a couple of questions about this new feature.

1. What is the specific configuration value that you are trying to access?
2. Have you ever consider the security implications of this change? This is given that some sensitive information is stored in the configuration files(e. g. db and message broker access) and an OpenStack admin can differs from Operating System admin.
3. Usually clients have interaction with tenant networks, do you think that isn't enough?

[Launchpad Janitor (janitor)]

[Expired for neutron because there has been no activity for 60 days.]