Add save, restore, and remove layout support (closes #32)

Add save, restore, and remove layout support (closes #32)

- Added save_layout, restore_layout, remove_layout commands
- Added Origami.sublime-settings file
- Added Origami to Preferences > Package Settings menu
- Added README and Keybindings to Origami menu
- Updated CONTRIBUTORS file

(I apologize for some of the indent changes my Python Linter attempted to change - I tend to use PEP 8 when I code, but I didn't want to alter your working code)