Create Models for DB

Create Model for each database table. 

basic struct template
col 1: name 
col 2: data type
col 3: json key name 

type ToDoList struct {
	ID        primitive.ObjectID   `json:"_id,omitempty"  bson:"_id,omitempty"`
	Task     string                       `json:"task,omitempty"`
	Status  bool                         `json:"status,omitempty"`
}