Eliminate the need to initialize geocoder

To get geocoder object just call locationlib.getGeocoder()
Method codeLatLng renamed to reverseGeocode

This is what the geocoder performs when passing latLng
Added new methods to locationlib

New methods:
reverseGeocode: function (lat, lng, callback);
geocode: function (address, callback);
getCurrentLocation: function (callback) ;
getCurrentLocationAsLatLng: function (callback) ;
getCurrentLocationAsString: function (callback);

Fixed asynchronous methods within locationlib: the callback is passed as
a parameter