RAVE alerts add check for "[CLEAR]" token

[AlanBCole]

Recent changes to the rave_alerts module fixed the issue we had with rave_alerts occasionally breaking web express sites but it changed the workflow for the people who manage the alerts.

this issue:

1. determine the previous and desired workflow based around adding the [CLEAR] token to alert titles
2. study the previous state of the code around that token's use
3. reimplement it in a way that preserves the fix

[AlanBCole]

Previously the rave title token check flow was as follows:

1. set rave_alerts_display to 1 (truthy)
2. if [ACTIVE] token is in the title:
   • rave_alerts_active_event to 1
   • log 'ACTIVE token found'
3. if [CLEAR] token is in the title:
   • set rave_alerts_display to 0
   • set rave_alerts_active_event to 0
   • no logging of this event

The effect is that if no [CLEAR] token is found in the title an alert will display because the rave_alerts_display variable is set outside of the conditional logic. However the only way to log anything was to include the [ACTIVE] token.