[REFACTOR] Move various Eclipse-independent classes to core

This includes:
- Preference constants
- Interfaces for the Saros DI container
- Some (not all) of color storage

Change-Id: I68a299dfd7b8ed4cd8562206ae88d16d1449670e
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1489
Tested-by: Jenkins CI
Reviewed-by: Andrej Szaffranietz <a.szaffranietz@gmail.com>
Reviewed-by: Bernd Bieber <brotlee@zedat.fu-berlin.de>
Reviewed-by: Arndt Lasarzik <alasarzik@gmail.com>
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>