Check for existing movies table when upgrading db.

- Also properly close cursors when upgrading to db v323.
- Also do some exists checks on older upgrades.
Push version to 15.0.2, 15003.
Do not crash if decoding image fails b/c of memory issues.

- https://crashlytics.com/seriesguide/android/apps/com.battlelancer.seriesguide/issues/537e080be3de5099ba3d2cb5
- Also fail if image size is anything below 1 byte.
Do not crash if account creation fails at first attempt.

- https://crashlytics.com/seriesguide/android/apps/com.battlelancer.seriesguide/issues/537cfc4ce3de5099ba3c3569
Change log for 15.0.2.
Merge branch 'fix-15.0.2'