[Java][Play] Enhancements to the Play generators

[wing328]

Description

Here is a list of enhancements:

• Change bin/java-play-framework-petstore-server.sh to "executable" (chmod a+x bin/java-play-framework-petstore-server.sh)
• Run bin/java-play-framework-petstore-server.sh to generate Petstore sample and add the files to this project.
• Test Petstore play server code in Travis CI
• Remove dependency on Swagger-Play
• Update README with more information (example)

Please reply to this if anyone has other feedbacks/suggestions

Swagger-codegen version

Latest master

Command line used for generation

bin/java-play-framework-petstore-server.sh

Related issues/PRs

#4943

[JFCote]

I will work on the following improvements in the next days/weeks

• Make the ControllerImplementor implements an interface as a CLI options. This is helping code generation when in a IDE each time the code is generated. By default, it will be to true.
• Completely remove swagger-play as a dependency and use the provided json instead of "generating" the json from the annotations.

[JFCote]

@wing328 Can you assign me to this issue. I will soon submit PR about this.

[wing328]

I cannot assign it to you since Github only allows issue to be assigned to "members" of the project only.

[JFCote]

@wing328 : Ok no problem :)

[wing328]

Added CI test via #5130

[JFCote]

@wing328 I think this can be closed. I'm pretty sure everything has been done for a long time. Let me know if something is missing.