Override mouseDown with touchstart

It would really be helpful and awesome if there was a directive for touchstart, even better would be if mousedown would overridden with touchstart just like touch does for click.

[MGray55]

+1 - would be very useful

[bartronx7]

yes!

[adamada88]

+1!

[IgorMinar]

unless I'm missing something, this should be pretty trivial to implement. are there some corner-cases we should consider?