Merge pull request #22 from nacabaro/database/items

Add items functionality

Forgot to push the updated db

Here comes the train (with more things)
- Updated available items
- Created ItemsScreenController
- Moved the ItemsScreen to keep code organized

Things
- Added items store and a way to switch between the store and your items
- Added an items dialog, click on it to see details of the item (description, amount) and use it
- Added items store, it lists all the items available

Things items related
- Added a MyItems screen
- Added an ItemElement placeholder
- Included database with all the items in the app (not final)
- Also included some demo items

As of now items don't do anything, i'm still making the UI