improved detail view
Merge pull request #19 from Hawk-It/Create_Edit

improved detail view
Refactoring the ListingsGridFragment.

- Start using Item instead of Media for the data in the ListingsGridFragment.
- Ordering item by Ascending updated date, so that the newer items show up first.
- Added a primaryMedia column for an Item. This will contain the mediaId for the Primay Media for this Item.
  primaryMedia is single media to be shown in list fragments.
Merge branch 'refactor_listing_fragment' of https://github.com/Hawk-It/HawkItAndroidApp into refactor_listing_fragment