Transfer xib views in a storyboard for native iOS 7

Also involved cleaning up controllers to make sure they worked in with the storyboard
and used segue to transfer between views.
Fix favourite list for Native iOS 7 implementation

When viewing the property details of an entry in the favourites list, if that
property is un-favourited then the favourite list was not updated after the
back ('< Favourites') button got pressed.
Add property table cell logic into storyboard for native iOS7

Also added a default image to property table cells.

Table views can use prototypes to define layout of cells.
Add delegate to respond to keyboard search button on iOS 7
Update UI for Property Search page on iOS 7

... to make use of storyboard features
Update model to use NSUInteger for iOS 7
Merge pull request #286 from matthewdunsdon/ios7-cleanup

Update iOS 7 implementation to take advantage of xcode's storyboard