[#1717] Fix javadoc failure  if too much files to process (command string too long) 

[#1718] Javadoc : Add link to JAVA Api and to play framework API 
[lighthouse #1717](http://play.lighthouseapp.com/projects/57987/tickets/1717)
[lighthouse #1718](http://play.lighthouseapp.com/projects/57987/tickets/1718)