nomiddlename/log4js-node — pull request #65 by teerapap (2012-04-15 19:34:27+00:00)
Title: Add flush method to Logger. Currently support only in file appender

When I push some log messages before calling ```process.exit(0)```, I encountered a problem that the messages aren't flushed to the file because ```flushBufferEvenIfCannotWrite()``` does not work and process exits.

So I added flush method with callback to make sure that the messages have been flushed to the file before I invoke ```process.exit(0)```