force using proxy_url for some requests

[bevenky]

action in elements, url in redirect and callbackurl in dial and conference should use proxy_url by default. all restxmls which are fetched should also use proxy_url.

just blindly set to use proxy for items above, so even if there is no proxy url mentioned in config, it will continue to work correctly, as this is already handled in code.

[bevenky]

done