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