Added ImageLoader to load images for each news.

Also changed label for an Activity and added library for markdown parsing (for the text in the summary)
Added navigator helper method in base classes
Use navigator() method in Fragment, setup action bar in details activity
Give some love to NewsDetails!

Display more data and in a fancier way (parse the markdown using a lib)
Show the image as well with the ImageLoader
Share a news with the ShareActionProvider
Open news URL in browser