When adding groups, add more than just the 9 first users

https://confluence.atlassian.com/display/CRUCIBLE/Choosing+reviewers says:

"When a group has more than 9 members, only the first 9 are added automatically. Any remaining members of the group must be added individually."

That artificial limitation is causing problems in our team. We need to have a higher number or, at least, make it configurable so we can raise it.