added refreshOverlay and listener to re-position markerviews in case lat/lng change
updating readme for refreshOverlay() method
Merge branch 'master' of https://github.com/Lordnibbler/backbone.googlemaps

Include logic to prevent endless
loop of model/overlay position-change events

Conflicts:
	lib/backbone.googlemaps-min.js
	lib/backbone.googlemaps.js