Add Build.scala extra imports for Less config 

To use the includeFilter / exludeFilter examples in Build.scala, the Assets and LessKeys symbols need to be imported.
Merge pull request #3241 from jxtps/patch-1

Add Build.scala extra imports for Less config
Update jshint version to 1.0.1

This upgrade includes bugfixes.

https://groups.google.com/forum/#!msg/play-framework/6hKzKjubv0M/aOfY-wnpLZYJ
Merge pull request #3248 from WarFox/patch-4

Update jshint version to 1.0.1