This will allow validation to work if the default logging locations cannot be written to but the configuration is otherwise okay. This will be the case for users with custom nginx configurations that log to other places, such as syslog.
- expose an nginx:validate command that can be used to show validation information
- properly reference the invalid nginx config, rather than tell the user that another app's nginx config is invalid when deploying their own app
- allow a user to cleanup bad nginx config files out of band when they are blocking a deploy _without_ requiring knowing where that nginx config is
Note that this may have issues with generated nginx.conf files that depend on other apps or other parts of the nginx config. For now, this is acceptable, though it is something that needs to be field tested.
Closes#3162
