* Removed a bug where multiple copies of books could be added to database
* Only BookId's are stored with the user for quicker lookups (isbn currently)
* The Id's stored with books are actually a struct, this allows an append option
* Possible improvements to the store Id's
Fixed a couple of bugs with duplicate book entires
Only saves the book Id's to individual users, should save space/time
Merge pull request #10 from lettergram/master

Fixed a couple bugs and only share the "id" of each book (to save space)