Fix default CUSTOM_OAUTH_PARAMS in settings. (#550)
Fix default CUSTOM_OAUTH_PARAMS in settings. (#550)

In the case ENABLE_CUSTOM_OAUTH_BACKEND is False and CUSTOM_OAUTH_PARAMS
is not setup exception AttributeError is raised during the deployment.
raccoongang/edx-platform,raccoongang/edx-platform,raccoongang/edx-platform,raccoongang/edx-platform