Fixes event detection on Kindle Fire browsers

The mobile UA detection was not including Kindle Fire - this PR adds kindle detection to the `MOBILE_REGEX`. 

On the Kindle if `Hammer.NO_MOUSEEVENTS === false` many gestures are broken or fired twice due to the Hammer statemachines being triggered on both touch and mouse events. This PR ensures the Kindle Fire (but not other kindles, unfortunately due to crazy UAs) is detected as "mobile".

This may fix #160 but I could not reproduce.