Issue when config file name only contains digits.

[jdel]

I ran the proxy with a config file named 6500.yml, and the app just crashes with
Using custom config /ffrk-proxy-0.8.0/lib/../config/6050.yml
Failed to validate config file /ffrk-proxy-0.8.0/config/6050.yml
[Error: application.config: must be of type String: value was 6050]

If I change the name to include a single character, it works fine. I believe it has something to do with https://github.com/ThauEx/ffrk-proxy/blob/master/lib/config.js#L280 missing some conversion to string.

[ThauEx]

I will fix this on Sunday with a new release. So you can update your docker container.