Use PlayApp rather than PlayUtils

Also tighten up the naming requirements for the Play JAR.

[#58432326]
Introduce a PlayApp factory class

[#58432326]
Basic tests of PlayApp

[#58432326]
Rename PlayApp to PlayAppPre22

[#58432326]
Introduce abstract superclass of Play application classes

[#58432326]
Introduce Play 2.2 application class

[#58432326]
Plumb Play 2.2 support into Play container

[#58432326]
Add Play 2.2 support

[#58432326]
Start to distinguish Play versions clearly

[#58432326]
Delete PlayUtils

Move code into PlayApp class hierarchy.

[#58432326]