Fix touch events

Fix Touch events by subscribing to both mouse and touch events (when available).
Navigators fires only touch or mouse event so no performance degradation.

I created this pull request after viewing issue [#720](https://github.com/DmitryBaranovskiy/raphael/issues/720). I saw you are searching for a simple workaround to make both mouse and touch works on Raphael.

I plan to create an another pull to add support to HTML5 Pointer Events in order to support IE  10+.