Group name contains a dot cannot be saved in a project page

If a group name contains a dot e.g test.com , it couldn't be saved in the project page. See the attached screen shot.

Steps to reproduce.

1. Create a group contains a dot e.g test.com
2. Go to a project (Admin > Projects List), click edit under the "Crucible Settings"
3. Enter the group name under the "Default Reviewers" then save the page