SW-14 [partial] Creates StackExchangeAPI_Impl.js for implementing stack exchange api methods
SW-14 background process to fetch notifications and update notification store
@trivial Removes extra unused file
SW-19 Updates popup ui to show notification count and divider
@trivial Adds link and title to objects in notification store
@trivial Updates notification store only if there is update #performance gain
@trivial Updates stackoverflow icon
#7 Updates fromdate api to fromtime api
#1 Refactoring | Split background -> globals + api_methods + background js