#209 Sharing button is added, save-bug is fixed

- Sharing-button is added to support the share button
  (Currently url is hard-coded as 'http://example.com/<recording group-id>')
- Save bug is fixed
- Obtaining location data is changed to 3 stages
  1. make the best location-provider start gathering location data. 
  2-1. if the location data is obtained, return it.
  2-2. if recording is finished before the location data is obtained, return the last-known location(out of date).
         2-2-a. if the last-known location is also not available, return (0, 0).