adding tickMarks capability, addresses #80

will need to be expanded on further, will address that in a separate
issue.

Here's my jsfiddle: http://jsfiddle.net/dUYKC/1/

Oddly, for me, it renders the input value as well as the hidden handle, not sure why. Has that come up before?

Other than that, this should take care of #80. I'm going to open a separate issue (#158) with more enhancements regarding tickmarks.