Introduced the native packager plugin in place of the custom dist task
Fixes to get native packager working.

* Remote pattern matching so type error shows up
* Move native packager settings *First* so they don't override play settings on a project.
* Add compile:package-bin to the libraries list in the distribution.
Introduction of scripting around the use of the packager's new makeBashScript key
Bump native packager to latest milestone incorporating changes
Removed existing integration test for the "dist" task as it is no longer applicable.

Moved to 0.6.0 of the native packager.

Integrated with native packager script production.
 #1257 Extracted doc processing out of Play
Scaladoc Fix
Removed duplication
Extracted methods for readability.
Some minor improvements
Applied scalariform
Add environment variable 'PLAY_OPTS' to be able to configure system properties in Play.

With PLAY_OPTS, we can override JVM parameters, SBT configuration ... without any modification in Play's scripts.

See also https://github.com/playframework/Play20/pull/1184
Wrap PLAY_OPTS in %ENV_VAR%
fix Enumerator.scala scaladoc
#1242 Ensured JSON null gets parsed to JsNull
#1240 Ensured media range parameters can have slashes
Switched to using a connection keep alive flag
Improvements from review of new results approach
#1305 Started 2.2 migration guide and highlights
Fix root logger property name.