Improve HammerJS implementation
Improve HammerJS implementation

Fixes broken support for Windows Phone.  Adds support for concurrent
pinch and pan.

praneybehl/svg-pan-zoom,lsloss/svg-pan-zoom,vsajip/svg-pan-zoom,etyplt/svg-pan-zoom,Paulyoufu/svg-pan-zoom,Paulyoufu/svg-pan-zoom,etyplt/svg-pan-zoom,vsajip/svg-pan-zoom,ariutta/svg-pan-zoom,ariutta/svg-pan-zoom,lsloss/svg-pan-zoom,ariutta/svg-pan-zoom,praneybehl/svg-pan-zoom