log

[gabrielrussoc]

we need a very good logging api

[yancouto]

We need a simple logging API. I think this one would be perfect. Really really simple, easy to set up and use.
For ContestWatcher we'll need another one (this one doesn't write to file), so should we think about this now or then?

[victorsenam]

This one looks good. We should keep in mind that this is an npm package. Storing the log and any other log-keeping related policy should be done by the user.
I believe we should not worry about what we will do on ContestWatcher, specially on such unrelated matter.