Adding level checks on dynamic logging

using levels.toLevel and this.isLevelEnabled prior to emiting the event will prevent the appenders from being notified if the log level provided is below the loggers level.
fixing unit test

logger.log requires 2 params, and with the 1st being level and filtering the level, the log call must provide a level that will result in log messages
Merge pull request #3 from jci-fox/issue184_dynamicloglevels

Issue184 dynamicloglevels