Show timestamps on Graphs

[jmbrunskill]

Is your feature request related to a problem? Please describe. It's difficult to tell what timerange is represented by the historical temperature graph.

Describe the solution you'd like I think the system should always show say 24hours of data? Missing data recently would then show as a gap in the trend (or maybe a straight line), and if we don't have 24 hours of data it would be obvious. With a hardcoded 24hr timeframe, we could get away with just something saying "Temperature Trend - Last 24hours"

• [ ] Increase datapoints to 48 to align with the 24 hour timeframe (1 datapoint every 30minutes)

Describe alternatives you've considered

• [ ] Make the time range configuable
• [ ] Use current approach averaging the data over 3 days for a 3day trend with 30 datapoints, unless we have less than 24hrs of data
• [ ] Show 3 days of data, but put the date/time somewhere in the graph UI
• [ ] Easy way to switch between common selections e.g. last hour, last 4hrs, last 24hrs?

Additional context Add any other context or screenshots about the feature request here.

[AnushaUp]

This is what it looks like in the latest version of coldchain v0.5.6