Upgraded all dependencise of Play

* Didn't upgrade to hibernate-validator 5.1.0 because it adds a number of extra JEE dependencies that I'm not sure we want.
* async-http-client 1.8.x changed the package of cookies, the Cookie constructor, and the available properties.
   - Removed version property from Play cookies because AHC doesn't support it anymore
   - Added expires property to Play cookies because AHC does support it.
   - Made the Scala API return Option for maxAge and expires, returning None if the server doesn't set it, or Some if the server does.