* Make InlineCache use a soft (not weak) reference

Objects that are referenced only by a weak reference will be eagerly
collected on the next GC run. Using a soft reference ensures that the
referent is only collected when there is memory pressure.

This should improve the utilization of the cache and reduce the need to
repopulate it.

See discussion in https://stackoverflow.com/a/299702/29470 for example.

* Exclude InlineCache.cache from MiMa

This variable should have been private in the first place. The class is
private[play] so it should be safe to break binary compatibility.

…lly (#8087)

* Use Akka's Reason when shutting down and disable Artery

* Organize imports of Akka.scala

* Run the stopHook after ActorSystemProviderSpec

Ensure that Akka, Play and Lagom all default to enabling coordinated
shutdown when downing.

This field was unused. On top of that, it was reloading the
HttpConfiguration more often than required. This could result in
warnings about the use of deprecated config parameters such as
`play.crypto.secret` on every connection.

This can be used by Lagom to remove the need to copy and paste all of
the ActorSystemProvider.start code in LagomApplicationLoader.scala.

See https://git.io/vbM3g

Using regular routes instead of WebCommands.