Address various speedtest exceptions

[owenleonard]

Speedtest frequently fails to find the best server on the hour. Google searches revealed this to be due to high server load. To address this, I added a retry attempts controlled by an environment variable.

I have also see speedtest fail to retrieve the config, so I've included exception handling for it as

Additionally, I defaulted the results to 0.0 so you can see in the graph when speedtest failures

Add missing utf-8 charset to index.html

[owenleonard]

@roest01 For some reason the update deps for v1.4 commit was causing the stats page to hang. I'm assuming it is because the yarn.lock file wasn't also updated, but I've never used yarn so I don't know for sure.