UrlBlocker should have consistent defaults

I find the following default kwargs for UrlBlocker odd:

allow_localhost: false, allow_local_network: true

This results in callers having to do:

Gitlab::UrlBlocker.validate!(uri, allow_local_network: false)

https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/gitlab/proxy_http_connection_adapter.rb#L17

Should we make this allow_localhost and allow_local_network have the same default values ?

Links

https://gitlab.com/gitlab-org/gitlab-ce/blob/master/lib/gitlab/url_blocker.rb#L11