Ignoring .DS_Store file
Fixed use of require in main.js

Used paths to simplify the **require** call.  Fixing this fixed
**index-require.html**.
Fixed useage of require in Sudoku.js

Used **paths** in the `require.config()` call to simplify the define
statement.
Added index-require.html

I added index-require.html to test the use of require in the project.
I will eventually replace index.html with the contents of this file.