0.6.10
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
adding ability to check if a logger exists

This allows for not accidentally adding a non-configured logger
Merge pull request #186 from jci-fox/issue184_dynamicloglevels

Adding level checks on dynamic logging
Merge branch 'master' of https://github.com/nomiddlename/log4js-node
0.6.11
Merge pull request #187 from jci-fox/addHasLogger

adding ability to check if a logger exists
0.6.12
Update README.md