Merge pull request #2 from azariah001/patch-1

Patch 1
Issue #11 - Add examples for negative shadow values.

Added additional cards to show the negative value effect.
Issue #11 - Update  to account for negatives in JS

zchanged method updated to account for the use of negative values
Merge pull request #3 from azariah001/master

Issue #11 - Scripts and Demo updated for negatives