Add configurable ban options for WebUI

[Chocobo1]

• Expose WebUI ban counter to users
• Use QDeadlineTimer for tracking WebUI banned duration
  It simplifies our code and the new timer is monotonic.
• Fix coding inconsistencies in preferences.html
  1. Format table tags properly
  2. Add a proper label tag
  3. Don't use abbreviation for seconds, we use full name everywhere else
• Expose WebUI ban duration to users

Screenshot: GUI, WebUI