init() method needs to assign to "self" otherwise Xcode gives a warning.
@synthesize of @property is required for those projects that don't support auto-synthesis.
Need to instantiate VALocationManager on the main thread, otherwise it will never call back. (This is a restriction in CLLocationManager.)
Merge pull request #1 from panicinc/master

A bug fix, plus some changes to make VALocationManager more broadly compatible