Add tests

[kueda]

At a minimum, a test suite should assert that for each of these photos:

we expect that

• in iOS
  • metadata is returned
  • metadata includes DateTimeOriginal
  • metadata includes GPSLatitude
  • metadata includes GPSLongitude
  • metadata includes GPSHPositioningError
• in Android
  • metadata is returned
  • metadata includes DateTimeOriginal
  • metadata includes GPSLatitude
  • metadata includes GPSLongitude
  • metadata includes GPSHPositioningError