remove unnecessary classycle configuration from languageScala plugin

+review REVIEW-5273
Always use Zinc + compiler daemon in 'scala-language'

- extract useAnt functionality to scala project
- ScalaCompileOptions now subclass of PlatformScalaCompileOptions adding ant support
- languageScala main now is java only

+review REVIEW-5273
rename DefaultcalaToolChain to DownloadingScalaToolChain

+review REVIEW-5273
more cleanup on LanguageScala after review

- add some whitespaces
- removed unused classes

+review REVIEW-5273
reference JavaPlatform in PlayPlatform instead of using JavaVersion directly

- clarify: how to declare sourceCompatibility

+review REVIEW-5273