Add Play 2.8 support

[benmccann]

Play 2.8 mostly matches Play 2.7, but drops support for Scala 2.11 and uses a newer version of Twirl by default.

Travis is failing for all PRs right now. This won't change that. But it probably doesn't hurt to merge it since it's a pretty simple one

[apflieger]

There's an other reference to the version support here src/docs/asciidoc/00-intro.adoc

[stephane303]

How would it be possible to use this before it is merge and published to https://gradle.github.io/playframework/, as it takes forever to be done ?
I am working on a legacy play framework project using gradle, which I do not know very well, so any help for instructions to use the forked plugin would be very appreciated.

....
If anyone needs it, here is how you can do it:

https://proandroiddev.com/tip-work-with-third-party-projects-locally-with-gradle-961d6c9efb02

You will have to add this to settings.gradle, to import the plugin in your project

pluginManagement {
  repositories {
      mavenLocal()
      gradlePluginPortal()
  }
}

[JLLeitschuh]

Are there any tests that validate that this change works?

[benmccann]

I'm not familiar with the tests in this project. I would hope that they test each version. In any case, I'm no longer using this project, so I won't be updating this PR. Feel free to merge, update, or close as you see fit

[devYonz]

Bump on this change...

[JLLeitschuh]

@benmccann can you update your commits so they pass DCO?

[benmccann]

Done

I've also signed the Gradle CLA: gradle/gradle#268 (comment)

[ghost]

@JLLeitschuh Hi, sorry I am new to github. I was trying to push fixes into this PR, but it shows
remote: Permission to gradle/playframework.git denied to me.
I am not sure that I need Permission grant by your guys or I followed by wrong steps?

[cstroe]

@seyashizuo , you need to fork this repo to your account:

After that, clone your repository locally:

git clone git@github.com:cstroe/playframework.git
cd playframework

Then add benmccann's fork as a remote repository:

git remote add benmccann git@github.com:benmccann/playframework-1.git

Then fetch the changes on his play28 branch (this PR is made from that branch):

git fetch benmccann play28

And create your own local branch from it:

git checkout -b play28 benmccann/play28

Then you collaborate how you see fit (open PR to benmccann's fork to get changes into his brach, or open your own PR to this repository).

[JLLeitschuh]

Thank you @cstroe. @seyashizuo was not my intention to ignore you, I've just been really busy.

[JLLeitschuh]

@benmccann if you can rebase this on master, and add some test to verify that this works, as well as add information to the release notes, I'll be happy to merge this.

I will endeavor to respond quickly. Previously, this PR was blocked by getting CI working on master. Now that this is working, I'm more than happy to push this forward.

[benmccann]

I'm not using Play anymore at the moment. Someone else can feel free to take this over from me though if there's someone else interested in this

[JLLeitschuh]

I'm going to close this PR then. I welcome anyone else to take @benmccann's work here and bring it back to life as a new pull request. Please do insure that any new PR does have test coverage of that new play version. Thanks!