Concatenate route files
Use WebJars for external JS/CSS libraries
Publish assets when publish* commands are used

See https://github.com/playframework/playframework/issues/2846
Use spaces instead of tabs
Migrate samples to play2.3
Samples: use the concatenated routes file
Samples: use assets defined in the main project
get the right Scala version with %%
Update version of guice in order to fix an error

error was encountered with play2-cache-sample:
"java.lang.IncompatibleClassChangeError: class
org.objectweb.asm.tree.ClassNode has interface
org.objectweb.asm.ClassVisitor as super class"