Fix for #1497 and display Package Icon on page render

Fix for issue https://github.com/NuGet/NuGetGallery/issues/1497 

All browsers (Chrome, IE, Firefoxs) seems to submit the form if a user press enter while the focus is inside a <input type="text"...> box.
To prevent the submit I added a new eventhandler which fires on keypress. A simple fiddle can be found here: http://jsfiddle.net/bD9jN/1/

I also deleted a few lines unused code.

Other enhancement: Display the icon already on page render if available