Abhinav: Making the cell layout look neater.
Abhinav: Making the title slightly darker.
Nazneen: Added a progress dialog when the images are being fetched for the grid view.
Nazneen: Implementing callback mechanism.
Nazneen: Downloading images in background.
Abhinav : Implemented Caching.
Abhinav: Added the external storage functionality.
Nazneen: Removed unnecessary layouts.
Nazneen: Improved the layout using android-style.

Conflicts:
	res/layout/cell_layout.xml
Nazneen: Using SharedPreferences to avoid loader at the start of the app.