Removes serialized container support
Adds a Directory-based Scala Installation subclass
Hooks in Addition/Removal for Scala Installations

Limits custom versions to >= 2.10
Adds a ScalaInstallation serializer helper

Hooked in Scala Installation Serialization
Deals with deserializations, including that of bundles
Hardens scala jar detection in case of multiple suitable jars

Harden against non-binary-compatible {compiler, reflect, ...}.properties
Plugs in ScalaInstallation choices
Container edition triggers Scala Installation choice

Container edition sets the desired scala installation,
updates the compiler settings view from Pub/Sub model.
Rationalizes ScalaInstallationChoice usage
The builder is now explicitly connected to scala desired version resolution
 (previously only worked as a side-effect)