Retry in syncing resources

[jingtang10]

Is your feature request related to a problem? Please describe.
When syncing data from the client to the server there may be failures due to poor connectivity meaning the data is not properly sync'd

Describe the solution you'd like
Handle sync (upload/download) failures and retry appropriately.

When there is a sync failure, the SDK should:

• Retry in the background after waiting for X minutes
• Provide information back to the client as per the sync config

Provide sync configuration options to indicate:

• Retry period in minutes e.g. 10 minutes or 15 minutes
• Number of retries before changing the status to FAILED
• Whether to return sync status to the client