Added category to menu bar

Issue #80 

## Testing Instructions

- [ ] Open destiny and verify that you can see all the categories in the menu bar.
- [ ] Upon clicking on the link verify that you are redirected to the product listing of that category

 If there is no product for any category verify that:
  * - [ ] As a normal user you see the message NO Products Yet
  * - [ ] As a admin user you see the message NO Products Yet and Why don't you create One?