Added multiple configurations / changeable platform. + FREE BUILD

[FlorianKirmaier]

Similar to the other PullRequest,
Only took the idea of the other pull requests.

It would be great if this (or the other pull requests) could be merged!

Until then, feel free to use my fork:

repositories {
  gradlePluginPortal()
  maven {
    url "https://sandec.jfrog.io/artifactory/repo"
  }
}
dependencies {
  classpath 'org.openjfx:javafx-plugin:0.0.14-SNAPSHOT-FORK'
}

[abhinayagarwal]

Hi @FlorianKirmaier,

I feel configuration is superseded by configurations property. IMO, only latter should be enough.

[FlorianKirmaier]

I kept the setConfiguration method to make the PR was supposed to be compatible with the old code.

Thank you for looking into the PR!

Didn't know it was possible to continue to work on the branch of a PR, interesting!

[jperedadnr]

Looks good to me