Change the way we store exclusive access tickets in the store to prevent overwriting another device's ticket changes.

[FIXED]     Overwriting of other device's ticket changes in KVS.
[FIXED]     Don't remove observation of KVS & application events when clearing the store.
[UPDATED]   When cloud store is unavailable, don't fall back to the local store; wait for it to become available.
Remove desync avoidance.

[REMOVED]   Desync avoidance strategies were unreliable and only worked while all devices are online.