Tidied up the Play eclipse code and removed some apparently redundant logic. Also the method used to remove the scala nature from a .project file was a little fragile.
Add convenience methods for changeLang(Lang lang).
Merge pull request #1596 from huntc/play-eclipse-tidy

play-eclipse tidy-up
Merge pull request #1700 from smola/java/convenience-changelang

Add convenience methods for changeLang(Lang lang).
Merge remote-tracking branch: upstream/master