Added repository; refactor getgroceries from grocery module;
refactored delete grocery to repo
refactored clear grocery to repo; refactored persist and un-persist to repo from common
Refactored the repo; removed any UI dependencies, and always returns a promise.
Refactored the getProducts from product to repo
Refactored the all other products data access methods from product to repo
Refactored the repo; better flow
Fix the issue with background image not centering
Merge branch 'Repo'