Explicit PHP5 visibility and static declarations for bp-groups-classes.php

See #5108, #3886

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7316 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Explicit visibility and static declarations in bp-blogs-classes.php

See #3886, #5108

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7317 cdf35c40-ae34-48e0-9cc9-0c9da1808c22