Emit addition recess error information when error occurs.

This commit lets us do fun things like this gist: https://gist.github.com/shellscape/d60b941e78736c3ccd82 when an error occurs. 

The ```fileName``` property was being lost when PluginError was instantiated. (PluginError's constructors are problematic and inconsistent, I've opened an issue with gulp-util about it). So I'm manually attaching it to the instance to ensure that it's not lost.
this should be a local var