Add ergodox_ez keymap to match Kinesis Contoured.

[agriffis]

This keymap attempts to match the Kinesis Contoured (aka Advantage) default
layout as closely as possible. See
http://www.kinesis-ergo.com/wp-content/uploads/2013/06/advantage_layout_win.pdf

Apart from the obvious mappings, this keymap also:

• removes the dual-purpose momentary layer/normal keys: Z, /, and Grv;
  because the author--coming from a Kinesis keyboard--finds the delays and
  accidental modifiers to be more disconcerting than helpful.
• puts Esc in the bottom left since there's no place for it in the top
  left to match the Kinesis.
• changes the bottom-right key into an L2 toggle since there's otherwise no
  way to get to L2.
• adds PrScr, ScrLk and Pause to the L1 keymap, down the left side, since
  they're present on the Kinesis but not available in the default
  ergodox_ez keymap.

[agriffis]

This PR replaces #42

[ezuk]

@agriffis - looking great! Two thoughts:

1. It would be good if you could rename the file itself to keymap_kines-ish.c just to avoid any potential legal issues going down the road (trademarks etc.)

2. Could you grab the readme you wrote above and put it in keymap_kines-ish_README.md so that it remains available to all? (i.e, becomes part of the codebase)

I'd do it myself but I see the PR comes from your own repo, so figured I'd ask. :) Love this! Thank you!

[ezuk]

@agriffis - I can also do (2) above myself if you want once you rename the file.

[agriffis]

@ezuk Should be all set now.

[ezuk]

@agriffis - Beautiful! Merged, thank you so much! :)