Force line endings to Unix-style line endings for java and scala files

Added gitattributes to force java files to Unix-style line endings

Might cause problems with files that are currently CRLF or people who have CRLF files in their fork. Do you think it is a good idea to add this? (my git experience might be insufficient)

Also small possibility that some Windows tools don't work on LF files (solution: use better tools ;))

Sources:
https://coderwall.com/p/buf0rq
http://adaptivepatchwork.com/2012/03/01/mind-the-end-of-your-line/