Fix JSON media type

As defined in RFC 4627:
"The MIME media type for JSON text is application/json."
playVersion is not a setting, at least not in metabuild
Merge pull request #3005 from fernandoacorreia/application-json

Fix JSON media type
Merge pull request #3006 from OlegYch/patch-1

playVersion is not a setting, at least not in metabuild
Add Silhouette module
Update links in repo README
Merge pull request #3007 from cchantep/fix-3007

Documentation link is broken on home page
Anorm refactoring
Update to twirl 1.0.1
Merge pull request #2959 from cchantep/anorm-refact

Anorm refactoring
Merge pull request #3011 from pvlugter/twirl-1.0.1

Update to twirl 1.0.1