DeprecationWarning: prom-client ... when starting Rocket Chat server

[distlibs]

Description:

When I start Rocket Chat server using command meteor I get deprecation warning:
(STDERR) (node:8753) DeprecationWarning: prom-client - Passing a non-object to metrics constructor is deprecated

I think it can be related with:
RocketChat.metrics.messagesSent = new client.Counter('messages_sent', 'cumulated number of messages sent');
in packages/rocketchat-lib/server/lib/metrics.js.

If I change to this:
RocketChat.metrics.messagesSent = new client.Counter({'name': 'message_sent', 'help': 'cumulated number of messages sent'});
deprecation gone.

Server Setup Information:

• Version of Rocket.Chat Server: 0.61.0-develop (fbbe16c)
• Operating System: Ubuntu 16.04.3 64-bit
• Deployment Method(snap/docker/tar/etc): git pull
• Number of Running Instances: 1
• DB Replicaset Oplog: Enabled
• Node Version: 8.9.3 - x64

[geekgonecrazy]

Could you please open a PR with this change? Seems like your changes should fix it for everyone.

[jgtoriginal]

@geekgonecrazy I tested this solution and can confirm that it works. So just opened a PR as you suggested.
Thanks @distlibs for your collaboration.