Implement Node.js for Linux

Based on an earlier pull request from @timburgess, #278. This also includes commits from #305 that fix the installer build. Finally, I've updated the gyp and grunt scripts to include node.

Original description:

This is some initial work in getting the node process up & running in Linux.

With this code, brackets-shell kicks off a mutexed launch thread that starts the Node executable in a subprocess.
As per the latest linux setup script, Node is launched from brackets-shell/deps/node/bin/node.

A file descriptor in the startup thread is piped to STDIN in the subprocess.
I have experimented with passing input to the node process to eval(). This works but Node appears to buffer it's output if it detects that STDIN is not a terminal. If I run node in interactive mode i.e. 'node -i' it stops buffering but produces a lot more output than I think is wanted.

I'd appreciate getting some feedback on how to run Node as then I can add code to setup a pipe from the subprocess STDOUT to a thread that reads the output.