Fixes #3805, reverted change in log importer that looked for end-of-line after format regex match and modified format autodetection logic to pick the format based on whether the format matches and the number of groups returned in the match.

Notes:
  * Added several more tests to log importer tests.py. Added tests for checking format of log files w/ extra junk info on log lines. Added individual tests for parsing regex format.
  * Modified log files used in ImportLogs test, added extra junk info to end of some lines.
  * Fixed failing test in tests.py for the S3 log file format.
Use span instead of deprecated font tag [ci skip]
Fixes #3131, add new auto-updating widget that displays the number of visitors, visits and actions in the last N minutes.

Notes:
  - Added visitors metric to result of Live.getCounters.
Refs #3131, fixing build
Fix bug where manually clicking the 'Check for updates' link in header_message.tpl would show the 'You are using the current version' message even if there is a new version.