guard against missing timestamp, make distance and timestamp fit on one line

[sethvincent]

Closes #284

I'm pretty sure the error described in #284 was happening only because we had observations that were made back when we had that bug where timestamps weren't persisted.

I added this guard to make sure it doesn't cause an issue just in case.

I also made some changes to the styles to make sure distance and last updated are on the same line and give better spacing when the name of the feature is long enough to be on two lines.

Example:

[sethvincent]

Added a commit that makes it so the map overlay says Observation if there's only 1, and Observations in other cases.

[mojodna]

Working from Starbucks? Nice easter egg in that screenshot, @sethvincent

[sethvincent]