Zcoin Mining Pool Hub

https://zcoin.miningpoolhub.com

There were some internal issue related to zcoin servers. (It was not zcoin's issue, just pool server)
Not all zcoin servers were affected and this issue only blocked newly connection trying miners so I didn't notice this problem easily.

I believe all issues are resolved. I'll improve some other parts to make it not happen again.

Sorry for inconvenience.