Portable build

[pthiess]

As user, I'd like to run Brackets without running an installer and without making any changes to my computer outside the Brackets app folder. I want to place Brackets on a thumb drive and have it work the same on any computer I plug the thumb drive into.

This also provides an escape hatch for non-admin Windows users (but see #1004 for the "real" solution to that).

Criteria

• Preferences/cache stored in app folder, not global user folder
• Shell settings (e.g. window size) stores in app folder, not global user registry keys
• Look for extensions in app folder. Don't look in global user folder.
• Installing extensions places them in app folder, not global user folder.
• Disable all Brackets UI related to file associations.
• Any registry keys brackets-shell sets automatically on startup (e.g. ProgID) shouldn't be touched in portable version.

adobe/brackets-shell#333

• @JeffryBooher Review Code
• @JeffryBooher Test MAC
• @JeffryBooher Test Windows
• Add to build
• Host on brackets.io

[pthiess]

Successor of Trello card 1003.

[peterflynn]

Closed since the card has gone back to the Backlog - https://trello.com/c/sHyY0KlB/1003-portable-build