adding 'addRewrite' to winston, so that we can add extra information on the default logger.
[fix] catch exceptions for file transport unlinkSync

Using cluster, I sometimes run more than one winston logger on a
single instance. Occasionally they both detect that they should
remove the log file, and one will unlink before the other. This
adds a try...catch to make sure that the unlinkSync call doesn't
throw.
[fix] Be more defensive when working with `query` methods from Transports. Fixes #356.
Allow using logstash option with the File transport
Included the label from options to the output in JSON mode.
fix dates on transport test
[test] Add failing test for fix proposed in #365.
Added color for pre-defined cli set.
[fix test] Added failing tests for #396.
err can be a string
[test] Added failing tests for #404.
fix Logger#transports length check upon Logger#log
[test fix] Update failing test for #404 to be correct.
Add label option for DailyRotateFile transport

This option is missing from this transport but available in the others
[doc] Updated CHANGELOG.md for `winston@0.8.1`.
[dist] Version bump. 0.8.1
[fix] s/self/this. Fixes #470. Fixes #471.
[minor] Do not redefine `options`.
[test minor] Unwrap style madness in file-open-test.js and file-stress-test.js
Updating winston-graylog2 transport documentation