Moving config settings to magnum.conf.j2

As per a comment from jmccrory regarding the number of
config_overrides for the Magnum role, I've moved the
configuration settings from os-magnum-install.yml to
magnum.conf.j2.  I've also removed all comments and
empty sections from magnum.conf.j2 to make things clearer.

Change-Id: I60c870b29715d68f42a10313da70bb18468e13fb

defaults/main.yml

@@ -101,6 +101,7 @@ magnum_pip_packages:
   - Babel
   - MySQL-python
   - PrettyTable
+  - PyMySQL
   - PyYAML
   - SQLAlchemy
   - WSME

extras/os-magnum-install.yml

@@ -75,39 +75,6 @@
       magnum_galera_address: "{{ galera_address }}"
       magnum_venv_tag: "{{ openstack_release }}"
       magnum_venv_download_url: "{{ openstack_repo_url }}/venvs/{{ openstack_release }}/{{ ansible_distribution | lower }}/magnum-{{ openstack_release }}.tgz"
-      magnum_config_overrides:
-        DEFAULT:
-          host: "0.0.0.0"
-          rpc_backend: "{{ magnum_rpc_backend }}"
-        api:
-          host: "0.0.0.0"
-        database:
-          connection: "mysql://{{ magnum_galera_user}}:{{ magnum_galera_password}}@{{ magnum_galera_address }}/{{ magnum_galera_database_name }}?charset=utf8"
-        oslo_messaging_rabbit:
-          rabbit_hosts: "{{ rabbitmq_servers }}"
-          rabbit_port: "{{ rabbitmq_port }}"
-          rabbit_userid: "{{ magnum_rabbitmq_userid }}"
-          rabbit_password: "{{ magnum_rabbitmq_password }}"
-          rabbit_virtual_host: "{{ magnum_rabbitmq_virtualhost }}"
-          rabbit_use_ssl: "{{ rabbitmq_use_ssl }}"
-          rabbit_notification_exchange: magnum
-          rabbit_notification_topic: notification
-        keystone_authtoken:
-          identity_uri: "{{ keystone_service_internaluri }}"
-          insecure: "{{ keystone_service_internaluri_insecure |bool }}"
-          auth_type: "{{ magnum_keystone_auth_plugin }}"
-          auth_version: "v3"
-          signing_dir: "{{ magnum_system_user_home }}/cache/api"
-          auth_url: "{{ keystone_service_internaluri }}"
-          auth_uri: "{{ keystone_service_internaluri }}"
-          project_domain_name: "{{ magnum_service_project_domain_name }}"
-          user_domain_name: "{{ magnum_service_user_domain_name }}"
-          project_name: "{{ magnum_service_project_name }}"
-          username: "{{ magnum_service_user_name }}"
-          password: "{{ magnum_service_password }}"
-          memcached_servers: "{{ memcached_servers }}"
-          token_cache_time: 300
-          revocation_cache_time: 60
       tags:
         - "os-magnum"
     - { role: "openstack_openrc", tags: [ "openstack-openrc" ] }