Added callback onStart to be called right before animation.
Seriously, I hate spaces. Why doesn't sublime realize this?
#61 Add an active class to the current slide.

The active class can be defined but defaults to active
#61 Add an active class to the current slide.

The active class can be defined but defaults to active
Merge branch 'unslider_onStart' of https://github.com/Aaron3/unslider