Add view for group

Add a view and template for basic data of a group, including a list of group members (with links to the respective person).

changed milestone to %1.0a0

added part::frontend prio::1 type::feature labels

mentioned in merge request !13 (merged)

mentioned in commit 932e7f8b

mentioned in merge request !14 (merged)

mentioned in commit ecb44c44

mentioned in commit 2e27397d

closed