Changed conditions of periodic status update.

1. Request status for each pending task, even if there are some finished
   tasks already. For example, even though GitHub commits unblock Mooch,
   it will keep request status for CodeForces anyway.

2. Global okTime not needed anymore. We check expiration date of each
   task individually.
Bugfix: status check failed on null dates.
Removed unused global okDate.
Rename codeforces labels.
Apply changes in options immediately after saving.

This includes status refresh so that new login settings could have come
in effect.
Add About page