Add custom attributes to groups request/response

groups.go

@@ -47,6 +47,7 @@ type Group struct {
 	ParentID             int                `json:"parent_id"`
 	Projects             []*Project         `json:"projects"`
 	Statistics           *StorageStatistics `json:"statistics"`
+	CustomAttributes     []*CustomAttribute `json:"custom_attributes"`
 }
 
 // ListGroupsOptions represents the available ListGroups() options.
@@ -62,6 +63,7 @@ type ListGroupsOptions struct {
 	SkipGroups           []int             `url:"skip_groups,omitempty" json:"skip_groups,omitempty"`
 	Sort                 *string           `url:"sort,omitempty" json:"sort,omitempty"`
 	Statistics           *bool             `url:"statistics,omitempty" json:"statistics,omitempty"`
+	WithCustomAttributes *bool             `url:"with_custom_attributes,omitempty" json:"with_custom_attributes,omitempty"`
 }
 
 // ListGroups gets a list of groups (as user: my groups, as admin: all groups).