Integrate out-of-process node server into brackets shell (updated x 3)

(Note: This is a rebased (again (again)) version of the original node-process pull #178 (and later #187 (and later #200)), since master has changed significantly with native menus and other commits.)

Provides a first implementation of an out-of-process node server integrated into the brackets shell. Fully working for Mac and Windows. Includes tests in a separate Brackets extension.

To build, do exactly what you do for master.

To run, do exactly what you do for master.

To test (and understand how to use it), get this extension: https://github.com/joelrbrandt/brackets-node-client

Soon, there will be a branch in adobe/brackets that has the client code and tests integrated into core.