fixes #1704

Build, install and run:
gulp vscode-linux-packages
sudo dpkg -i out-linux/vscode-amd64.deb
code .

Installing the package does the following:
- Puts VSCode dir at /usr/share/code
- Puts code.sh launcher in /usr/bin
- Defines a .desktop file to properly integrate with the launcher

Fixes #2679

This script wraps the main code executable for Linux and OS X, redirecting
output to a file and running in the background. An exception is made when help
or version argument are used, not suppressing the output as the bootstrap.js is
expected to write to stdout and immediately exit.

Fixes #77