Does not work with `grunt-webpack`

[danoc]

Hello,

I'm trying to use this to report errors from grunt-sass, grunt-postcss, and grunt-webpack. It works for all but grunt-webpack.

I dug into the source code and suspect that it doesn't work because grunt webpack prints the output like this when you have failOnError set to false:

(Setting failOnError to true will cause the grunt process to exit completely which I don't want.)

I dug into the grunt-notify code to debug this, but couldn't find the right place to stick a console.log statement so that it prints the message that comes in.

Any tips? I'm happy to fork and submit a PR.