Non-lazy loaded configuration options depend on import order

[Erik Olof Gunnar Andersson]

Configuration options should always be lazy-loaded, this is to prevent changes in import order from interfering with the configuration variable being instantiated properly.

This is currently causing the following variables to always be set to their default values.
> agent_call_low_timeout
> agent_call_high_timeout
> agent_replication_snapshot_timeout
> remote_(nova|cinder|neutron)_client config

This is essentially a follow up to bug 1671655 that caused PROXY_AUTH_URL previously found in trove/common/remote.py to always be set to the default value: "http://0.0.0.0:5000/v2.0".
> PROXY_AUTH_URL = CONF.trove_auth_url

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/466923
Committed: https://git.openstack.org/cgit/openstack/trove/commit/?id=fcf75dfd60f3d717f967a07f18ff186205c374e9
Submitter: Zuul
Branch: master

commit fcf75dfd60f3d717f967a07f18ff186205c374e9
Author: Erik Olof Gunnar Andersson <email address hidden>
Date: Mon May 22 15:05:34 2017 -0700

    Lazy load all configuration options

    This is a follow up to Change #444040.

    Configuration options should always be lazy loaded,
    this is to prevent changes in import order from
    interfering with the configuration variable being
    instantiated properly.

    Change-Id: I3040108128ba56746ed4d5d688b8b8d33da753fc
    Closes-Bug: #1694538

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/trove 9.0.0.0b3 development milestone.