Fix Uemis downloader to download all matching dive infomration

The Uemis SDA returns the data for each dive from several different
databases. And oddly, the getDive data uses a different key than the
getDivelog data. We have always compensated for that by looking up the
correct key and applying the data to that dive, but unfortunately we
didn't adjust the loop to correctly retrieve the getDive data for the
dives that were downloaded. So depending on how big the offset between
those two keys was we wouldn't get all of the necessary data.

With this change we try one, calculate the offset and then restart the
loop. Insane, but appears to be the only way to make this work.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>