From the looks of the Travis CI failure, this could be the issue
causing failures. Not sure as I can't reproduce locally. However,
it is still an inconsistency and worth fixing.
Updated logger.js to support disabling all log writes.
Updated log4js.js shutdown function to disable log writes.
Added tests.
Update gitignore to ignore rolling date stream's test output.
loadAppender will check for a shutdown function exposed by
a loaded appender. If present, it will be cached so that the
shutdown function can execute it.
The intent here is that a Node application would not invoked
process.exit until after the log4js shutdown callback returns.
John Engler