added model classes & UI changes
Json Parsing for TopPaidApps & topFreeApps
added UicollectionView for TopPaidAppViewController
Added method to display data in uicollectionView
added search  method
PopUP animation methods added
added popupview to view details of app
added popupview for iPad
added wishList controller & handled wishList
added comments
added wishList for iPad
modified Names according to coding standard.
used TabBarcontroller.selectedIndex to switch between Tabs.
added KeyPaths in model class
added TANetworkOperationCenter Class to perform network operations
added network operations.
Added Testcases To Model
Merge pull request #1 from robosoft-chaitra/ModelBranch

Model branch merged with development