Change initial offset of byte parsing to account for URI Beacon ID

**Problem:** The Android UriBeacon client was incorrectly parsing the advertisementData format, failing to take into account the initial two bytes consisting of the URI Beacon ID.  This led to an incorrect parsing of the URI and strange data being displayed.  (See UriBeaconAdvertiserActivity, line 59/60 for the reference.)

**Solution:** Specify the offset in the parser code.  

**Before:**

![before](https://cloud.githubusercontent.com/assets/1236394/5227029/e396c9d0-76ed-11e4-8c7c-e9c214474f70.png)

**After:**  

![after](https://cloud.githubusercontent.com/assets/1236394/5227042/008a6006-76ee-11e4-95f4-4fe6019c0d9d.png)

I would move this next to the other constants further down.