Device detection of Node-Webkit

Because the user-agent string can be (easily changed) [https://github.com/rogerwang/node-webkit/wiki/Manifest-format#user-agent], one of the few ways to detect Node-Webkit is to look for the 'process' object and require() function. If they exist, Node support was enabled and 'process.version' will have the version of Node.js used to create the project.

However, if Node is (disabled) [https://github.com/rogerwang/node-webkit/wiki/Manifest-format#nodejs], the 'process' object won't exist and the project will be executed as if it was in a single instance of a browser anyway.
Fixed trailing whitespace
Tests for both Node and Node-Webkit
Merge pull request #1129 from videlais/patch-2

Device detection of Node-Webkit