add (not enabled anywhere) ota restore caching to sync logs
add test for payload caching
remove redundant exception
add cache invalidation and test for it
remove deprecation warnings
unused import
fix bugs with empty sync log id
switch test util to use RestoreConfig and add caching option
add functional caching test
fix iteration modification bug
tests for cache invalidation
Merge pull request #115 from dimagi/ota-restore-caching

Enable OTA restore caching on sync tokens + tests