Remove default error and warn levels

[basickarl]

It's not a good idea to have this by default.

Example: If I wish to use the following filter: ".*:myLevel" only. I will receive those logs AND every error and warn log. I wish to specifically filter these messages, but I can't. Other logs such as error:myOtherLevel is polluting now my feed.

This specific piece of code should be removed in the bragi/lib/canLog.js file:

    // set error and warn to be always on unless explictly disabled
    if(group.indexOf('error') === 0 || group.indexOf('warn') === 0){
        canLogIt = true;
    }