Make test status page work on Firefox

[islemaster]

@epeach noticed today that the test status page was silently failing to update on Firefox (while working fine on Chrome). After some investigation I narrowed the issue down to a failure to parse the test suite start time.

Chrome	Firefox

The default Ruby Time.to_s format %Y-%m-%d %H:%M:%S %z is parsed in Chrome but not in Firefox. As noted above, removing the space before the timezone %Y-%m-%d %H:%M:%S%z makes the time parse in both browsers, but it's also not a valid RFC2822 or ISO 8601 date which is what Date.parse is documented to accept. Therefore we are now using ISO 8601 (looks like 2017-06-15T12:46:11-07:00).

I also added doctype and charset metadata to the test status page to silence warnings showing up in Firefox's console. Because of that, you may want to view this diff without whitespace changes.

[islemaster]

Uh... Circle is failing to install yarn?

$ yarn --version
bash: line 1: yarn: command not found

yarn --version returned exit code 127

Action failed: yarn --version

I wonder what's up.