referrals: 1/2 generation routes, display route, partial frontend

route for generation/enabling of referral for user(s) done? the frontend
is mostly done, but functionality is not there yet. Route for finding
and displaying referral to user is done. Also the config option for
referral is there, in user page settings.

models.go

@@ -414,3 +414,15 @@ type ChangeMyPasswordDTO struct {
 	Old string `json:"old"`
 	New string `json:"new"`
 }
+
+type GetMyReferralRespDTO struct {
+	Code          string    `json:"code"`
+	RemainingUses int       `json:"remaining-uses"`
+	NoLimit       bool      `json:"no-limit"`
+	Expiry        time.Time `json:"expiry"` // Come back after this time to get a new referral
+}
+
+type EnableDisableReferralDTO struct {
+	Users   []string `json:"users"`
+	Enabled bool     `json:"enabled"`
+}