fix additional issue showing iOS reconfiguration window
1. Fix iOS configuration window displace problem
2. Enhance picture download speed
1. Fix configuration window automactially close problem.
2. Show error message if camera configuration is error.
3. Fix memory leak.
Pebble button mapping:
1. Single click buttons UP or DOWN to select previous or next camera.
2. Long press button SELECT to turn on/off IR for the current camera.
3. Double click button SELECT to zoom in/out the current snapshot.
4. When viewing an image larger than the Pebble screen, use buttons UP and DOWN to navigate the Pebble screen for visible area on the larger image. Use button SELECT to switch up/down or left/right operations for the buttons UP and DOWN.