Added preventDefaultAxis

Added property determining on which axis you want to prevent default
actions. For example if set to restrict the y axis, scrolling will only
work as long as the flick is vertical. If the flick is recognized as a
horizontal movement the scrolling will be blocked.
Merge pull request #10 from dmitrif/master

Shit sorry guys, I know this is well overdue :S 
I've been AFK for a long while, doing it now!