Adding the default recommended .gitattributes file

I've added the default recommended .gitattributes file. The settings in this file provide some basic functionality, but the one we care about is "text=auto". That handles the line endings, which means no more wall of pink (http://www.hanselman.com/blog/YoureJustAnotherCarriageReturnLineFeedInTheWall.aspx). 

More about line endings here: https://help.github.com/articles/dealing-with-line-endings