restructure into skeleton and solution dirs

There are now two new top-level directories: 
* `solutions` contains solutions for both w5d5's regular TTT and w6d2's jquery TTT project
* `skeleton` contains the regular TTT solution to be used as a skeleton for the jquery project

I left the `index.html` top-level so as not to break the live demo.

Can someone make sure everything looks ok? Then we'll have to update the instructions in the w6d2 project to direct them to the right directory.