Fixed leak when creating an instance of CLLocationManager

The locationManager is a retained property.
When alloc/init a new CLLocationManager instance its retainCount is 1. When assigning it to a retain property its count will be 2. Only 1 release will take place (on dealloc) and the CLLocationManager is left around having a retainCount of 1.

This is not a major problem because KeenClient is a singleton (and will therefore never dealloc), but for the sake of correctness this pull request.