Backport the following changes for grizzly
  https://github.com/sleepyorion/neutron/commit/5365ad0cd6019f7e1a81467c61c774ae62c1588f

  * Exposed the attribute for service
      workers = number of workers for quantum API workers

  * Also exposed the following parameters for wsgi:
      backlog - number of backlog request to configure
      tcp_keepidle - sets the value of TCP_KEEPIDLE in second for each server socket
      retry_until_window - number of seconds to keep retrying to listen
      use_ssl - enable SSL on the API server
      ssl_ca_file - CA certificate file to use to verify connecting clients
      ssl_cert_file - Certificate file to use when starting the server securely
      ssl_key_file - Private key file to use when start the server securely

  * Merged quantum.openstack.common.db.sqlalchemy for connection pool.
  * Required python-oslo-config >= 1.2.1
Combined multiple commits into single commit.