Project Purpose: Create todo app with lit element
///// Previous installement for project /////
*** install npm and polymer => follow steps on https://polymer-library.polymer-project.org/2.0/docs/tools/polymer-cli
///// For run project /////
*** run "npm install" for "lit-element" or use "https://unpkg.com/lit-element@2.0.0-rc.5/lit-element.js?module" on Todo.js and TodoItem.js for lit-element.js
*** run "npm start"