Inconsistent use of terms Assignee and Attendee

[karthikb351]

Assignee and Attendee seem to be used interchangeably. This is especially evident in the report generation, where the models say 'assignee', but we map it to the 'attendee' in the report.

We also say 'attendee' in the frontend forms and the POST data keys.

We even use them interchangeably on issues and PRs:
-> q=attendee
-> q=assignee