Adds the slider with the drag, and step functions.

Adds drag, step, and comments giving the options available. I removed
the + and - buttons as per Geoff's requests.
Adds unit tests made for the slider

Adds the unit test we did so other groups in the future can have an
easier time with this portion.
Adds updates to the readme for a couple people of my group.
Merge pull request #108 from tabersays/master

The slider widget is ready.