Add first version of "Workman Dead" as an alternative layout.

- Add info to README.md to explain "Workman Dead" layout and
  show how to use a 'dead' key.
- Add screenshots for different states of the "Workman Dead".
- Add an SVG file than is similar to header of workmanlayout.com
  website.
Improve folder structure for Mac bundle screenshots

- Add license text for Workman-Dead.icns
Add description and screenshots for other alternative layouts.
Update README.md
Update README.md
Merge pull request #8 from spamwax/alternative-dead

Add first version of "Workman Dead" as an alternative layout.