[Fix Bug 907671] Make error message appear when optin box is not checked.
[Fix Bug 907658] Changing GROUPS_PER_PAGE setting to 20.
Merge pull request #581 from juliaelman/907658-fix-single-groups-display

[Fix Bug 907658] Changing GROUPS_PER_PAGE setting to 20.
Merge pull request #580 from juliaelman/907671-add-optin-error

[Fix Bug 907671] Make error message appear when optin box is not checked.