ENH: When creating a log entry, add current value of displayClasses

[jschrempp]

clientInfo.displayClasses holds information used by the checkin screen. Today it holds css class designations that are used to decorate clients differently. For example a value of "staff" would result in the person's displayed rectangle border being magenta.

We have found that this information is useful in reporting. For example, we report on unique members in the makerspace each day of the last year.

When a client is no longer a staff member, then "staff" is removed from their displayClasses. When a member joins as staff, then "staff" is added to the displayClasses. Since this info is kept in clientInfo, changing it also changes all historical reporting.

Proposed solution: Add a field "currentDisplayClasses" to the rawdata table. When a record is added to the rawdata table, set this new field to the current value of displayClasses for the client. Then change our reports to filter based on rawdata.currentDisplayClasses rather than clientInfo.displayClasses.