start setting up messaging b/w content and background scripts
remove popup.js
add firebase dep to manifest
update background script to put user and recent post data in local storage
add example use of messaging to background.js
Merge pull request #8 from aaromp/master

add post label
Merge pull request #7 from jrhdoty/master

update background.js to store user and post data in recent storage
update manifest.json