Bugfix Pingdom.php: Wrong errortime if no errortime exists

Assumed an error has occured at some time since creation of checks,
but if not, value will be null which causes `elapsedTime()` method to
miscalculate. Default to `created` time if no error has ever occured.
Bugfix: clearfix class misnamed

clrfix -> clearfix
Merge pull request #25 from myqlarson/develop

Fixed: pingdom time calculations and views