Add explicit sync feature

[barbeau]

Is your feature request related to a problem? Please describe.
There have been issues with data not showing up as expected server-side after data collection. After some time, it appears. It's not currently clear if this is a user issue with the device not being connected to the Internet when needed or a Firebase sync issue.

Describe the solution you'd like
It would be nice to have an explicit "sync" button/feature that would explictly push data to the server when triggered to ensure that data is pushed in a timely fashion, including an error message if sync fails.

We should also look to see if we can add a timestamp to record when the sync happens so we know how much data has been sync'd to the server.

I'm not sure this is currently possible with Firebase but we can investigate.