Fixed bug causing [ReferenceError: Process is not defined] messages while debugging in WebStorm.

It took me a long time to find the bug, but I finally did. Whenever I use [Jade] in my node applications I get a whole bunch of [ReferenceError: process is not defined] in the console while debugging in [WebStorm](http://www.jetbrains.com/webstorm/).

http://stackoverflow.com/questions/17812371/nodejs-jade-referenceerror-process-is-not-defined

I'm not exactly sure why this happens only while debugging but including `process` and `Buffer` in the vm context seems to fix the issue.