Issue 48 typed schema

[saracalihan]

type and optional default value added to schema usage.

Data types:

• String
• Boolean
• Date
• Number
• Array
• Object:

import { Types } from 'metronom';
const userModel = metronom.define(
// const userModel = new Model(
  {
    name: {
      type: Types.String,
    },
    surname: {
      type: Types.String,
    },
    age: {
      type: Types.Number,
      default: 1
    },
    isAdmin: {
      type: Types.Boolean,
      dafeult: false,
    }
  },
  'users',
  { 
    keyUnique: 'name',
    // set `flexSchema` to true and never define schema
  }
);