Stable Release 4.0.3

Addresses the following changes:

New API in core.js which allows a common interface for reading and writing to storage. #15, #16
Seperate UI and backend code. #16
Support for adding links via keyboard shortcut - Default is Ctrl + Shift + L #14
Support for downloading your links as JSON. #13
Minor UI changes.
Fix to minor breaking changes in #22 , #24

Thanks to all @kav2k for the suggestions and contributions.