MM-11120 Adding setting to disable email invitations and rate limiting. (#9063)

* Adding setting to disable email invitations.

* Adding a setting and rate limiting for email invite sending.

* Modifying email rate limit to 20/user/hour

* Adding EnableEmailInvitations to client side config and command.

app/team.go

@@ -805,6 +805,10 @@ func (a *App) postRemoveFromTeamMessage(user *model.User, channel *model.Channel
 }
 
 func (a *App) InviteNewUsersToTeam(emailList []string, teamId, senderId string) *model.AppError {
+	if !*a.Config().ServiceSettings.EnableEmailInvitations {
+		return model.NewAppError("InviteNewUsersToTeam", "api.team.invite_members.disabled.app_error", nil, "", http.StatusNotImplemented)
+	}
+
 	if len(emailList) == 0 {
 		err := model.NewAppError("InviteNewUsersToTeam", "api.team.invite_members.no_one.app_error", nil, "", http.StatusBadRequest)
 		return err
@@ -842,7 +846,7 @@ func (a *App) InviteNewUsersToTeam(emailList []string, teamId, senderId string)
 	}
 
 	nameFormat := *a.Config().TeamSettings.TeammateNameDisplay
-	a.SendInviteEmails(team, user.GetDisplayName(nameFormat), emailList, a.GetSiteURL())
+	a.SendInviteEmails(team, user.GetDisplayName(nameFormat), user.Id, emailList, a.GetSiteURL())
 
 	return nil
 }